Project acronym ABYSS
Project ABYSS - Assessment of bacterial life and matter cycling in deep-sea surface sediments
Researcher (PI) Antje Boetius
Host Institution (HI) ALFRED-WEGENER-INSTITUT HELMHOLTZ-ZENTRUM FUR POLAR- UND MEERESFORSCHUNG
Country Germany
Call Details Advanced Grant (AdG), LS8, ERC-2011-ADG_20110310
Summary The deep-sea floor hosts a distinct microbial biome covering 67% of the Earth’s surface, characterized by cold temperatures, permanent darkness, high pressure and food limitation. The surface sediments are dominated by bacteria, with on average a billion cells per ml. Benthic bacteria are highly relevant to the Earth’s element cycles as they remineralize most of the organic matter sinking from the productive surface ocean, and return nutrients, thereby promoting ocean primary production. What passes the bacterial filter is a relevant sink for carbon on geological time scales, influencing global oxygen and carbon budgets, and fueling the deep subsurface biosphere. Despite the relevance of deep-sea sediment bacteria to climate, geochemical cycles and ecology of the seafloor, their genetic and functional diversity, niche differentiation and biological interactions remain unknown. Our preliminary work in a global survey of deep-sea sediments enables us now to target specific genes for the quantification of abyssal bacteria. We can trace isotope-labeled elements into communities and single cells, and analyze the molecular alteration of organic matter during microbial degradation, all in context with environmental dynamics recorded at the only long-term deep-sea ecosystem observatory in the Arctic that we maintain. I propose to bridge biogeochemistry, ecology, microbiology and marine biology to develop a systematic understanding of abyssal sediment bacterial community distribution, diversity, function and interactions, by combining in situ flux studies and different visualization techniques with a wide range of molecular tools. Substantial progress is expected in understanding I) identity and function of the dominant types of indigenous benthic bacteria, II) dynamics in bacterial activity and diversity caused by variations in particle flux, III) interactions with different types and ages of organic matter, and other biological factors.
Summary
The deep-sea floor hosts a distinct microbial biome covering 67% of the Earth’s surface, characterized by cold temperatures, permanent darkness, high pressure and food limitation. The surface sediments are dominated by bacteria, with on average a billion cells per ml. Benthic bacteria are highly relevant to the Earth’s element cycles as they remineralize most of the organic matter sinking from the productive surface ocean, and return nutrients, thereby promoting ocean primary production. What passes the bacterial filter is a relevant sink for carbon on geological time scales, influencing global oxygen and carbon budgets, and fueling the deep subsurface biosphere. Despite the relevance of deep-sea sediment bacteria to climate, geochemical cycles and ecology of the seafloor, their genetic and functional diversity, niche differentiation and biological interactions remain unknown. Our preliminary work in a global survey of deep-sea sediments enables us now to target specific genes for the quantification of abyssal bacteria. We can trace isotope-labeled elements into communities and single cells, and analyze the molecular alteration of organic matter during microbial degradation, all in context with environmental dynamics recorded at the only long-term deep-sea ecosystem observatory in the Arctic that we maintain. I propose to bridge biogeochemistry, ecology, microbiology and marine biology to develop a systematic understanding of abyssal sediment bacterial community distribution, diversity, function and interactions, by combining in situ flux studies and different visualization techniques with a wide range of molecular tools. Substantial progress is expected in understanding I) identity and function of the dominant types of indigenous benthic bacteria, II) dynamics in bacterial activity and diversity caused by variations in particle flux, III) interactions with different types and ages of organic matter, and other biological factors.
Max ERC Funding
3 375 693 €
Duration
Start date: 2012-06-01, End date: 2018-05-31
Project acronym ACCOMPLI
Project Assembly and maintenance of a co-regulated chromosomal compartment
Researcher (PI) Peter Burkhard Becker
Host Institution (HI) LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN
Country Germany
Call Details Advanced Grant (AdG), LS2, ERC-2011-ADG_20110310
Summary "Eukaryotic nuclei are organised into functional compartments, – local microenvironments that are enriched in certain molecules or biochemical activities and therefore specify localised functional outputs. Our study seeks to unveil fundamental principles of co-regulation of genes in a chromo¬somal compartment and the preconditions for homeostasis of such a compartment in the dynamic nuclear environment.
The dosage-compensated X chromosome of male Drosophila flies satisfies the criteria for a functional com¬partment. It is rendered structurally distinct from all other chromosomes by association of a regulatory ribonucleoprotein ‘Dosage Compensation Complex’ (DCC), enrichment of histone modifications and global decondensation. As a result, most genes on the X chromosome are co-ordinately activated. Autosomal genes inserted into the X acquire X-chromosomal features and are subject to the X-specific regulation.
We seek to uncover the molecular principles that initiate, establish and maintain the dosage-compensated chromosome. We will follow the kinetics of DCC assembly and the timing of association with different types of chromosomal targets in nuclei with high spatial resolution afforded by sub-wavelength microscopy and deep sequencing of DNA binding sites. We will characterise DCC sub-complexes with respect to their roles as kinetic assembly intermediates or as representations of local, functional heterogeneity. We will evaluate the roles of a DCC- novel ubiquitin ligase activity for homeostasis.
Crucial to the recruitment of the DCC and its distribution to target genes are non-coding roX RNAs that are transcribed from the X. We will determine the secondary structure ‘signatures’ of roX RNAs in vitro and determine the binding sites of the protein subunits in vivo. By biochemical and cellular reconstitution will test the hypothesis that roX-encoded RNA aptamers orchestrate the assembly of the DCC and contribute to the exquisite targeting of the complex."
Summary
"Eukaryotic nuclei are organised into functional compartments, – local microenvironments that are enriched in certain molecules or biochemical activities and therefore specify localised functional outputs. Our study seeks to unveil fundamental principles of co-regulation of genes in a chromo¬somal compartment and the preconditions for homeostasis of such a compartment in the dynamic nuclear environment.
The dosage-compensated X chromosome of male Drosophila flies satisfies the criteria for a functional com¬partment. It is rendered structurally distinct from all other chromosomes by association of a regulatory ribonucleoprotein ‘Dosage Compensation Complex’ (DCC), enrichment of histone modifications and global decondensation. As a result, most genes on the X chromosome are co-ordinately activated. Autosomal genes inserted into the X acquire X-chromosomal features and are subject to the X-specific regulation.
We seek to uncover the molecular principles that initiate, establish and maintain the dosage-compensated chromosome. We will follow the kinetics of DCC assembly and the timing of association with different types of chromosomal targets in nuclei with high spatial resolution afforded by sub-wavelength microscopy and deep sequencing of DNA binding sites. We will characterise DCC sub-complexes with respect to their roles as kinetic assembly intermediates or as representations of local, functional heterogeneity. We will evaluate the roles of a DCC- novel ubiquitin ligase activity for homeostasis.
Crucial to the recruitment of the DCC and its distribution to target genes are non-coding roX RNAs that are transcribed from the X. We will determine the secondary structure ‘signatures’ of roX RNAs in vitro and determine the binding sites of the protein subunits in vivo. By biochemical and cellular reconstitution will test the hypothesis that roX-encoded RNA aptamers orchestrate the assembly of the DCC and contribute to the exquisite targeting of the complex."
Max ERC Funding
2 482 770 €
Duration
Start date: 2012-02-01, End date: 2017-01-31
Project acronym ACCRETE
Project Accretion and Early Differentiation of the Earth and Terrestrial Planets
Researcher (PI) David Crowhurst Rubie
Host Institution (HI) UNIVERSITAT BAYREUTH
Country Germany
Call Details Advanced Grant (AdG), PE10, ERC-2011-ADG_20110209
Summary Formation of the Earth and the other terrestrial planets of our Solar System (Mercury, Venus and Mars) commenced 4.568 billion years ago and occurred on a time scale of about 100 million years. These planets grew by the process of accretion, which involved numerous collisions with smaller (Moon- to Mars-size) bodies. Impacts with such bodies released sufficient energy to cause large-scale melting and the formation of deep “magma oceans”. Such magma oceans enabled liquid metal to separate from liquid silicate, sink and accumulate to form the metallic cores of the planets. Thus core formation in terrestrial planets was a multistage process, intimately related to the major impacts during accretion, that determined the chemistry of planetary mantles. However, until now, accretion, as modelled by astrophysicists, and core formation, as modelled by geochemists, have been treated as completely independent processes. The fundamental and crucial aim of this ambitious interdisciplinary proposal is to integrate astrophysical models of planetary accretion with geochemical models of planetary differentiation together with cosmochemical constraints obtained from meteorites. The research will involve integrating new models of planetary accretion with core formation models based on the partitioning of a large number of elements between liquid metal and liquid silicate that we will determine experimentally at pressures up to about 100 gigapascals (equivalent to 2400 km deep in the Earth). By comparing our results with the known physical and chemical characteristics of the terrestrial planets, we will obtain a comprehensive understanding of how these planets formed, grew and evolved, both physically and chemically, with time. The integration of chemistry and planetary differentiation with accretion models is a new ground-breaking concept that will lead, through synergies and feedback, to major new advances in the Earth and planetary sciences.
Summary
Formation of the Earth and the other terrestrial planets of our Solar System (Mercury, Venus and Mars) commenced 4.568 billion years ago and occurred on a time scale of about 100 million years. These planets grew by the process of accretion, which involved numerous collisions with smaller (Moon- to Mars-size) bodies. Impacts with such bodies released sufficient energy to cause large-scale melting and the formation of deep “magma oceans”. Such magma oceans enabled liquid metal to separate from liquid silicate, sink and accumulate to form the metallic cores of the planets. Thus core formation in terrestrial planets was a multistage process, intimately related to the major impacts during accretion, that determined the chemistry of planetary mantles. However, until now, accretion, as modelled by astrophysicists, and core formation, as modelled by geochemists, have been treated as completely independent processes. The fundamental and crucial aim of this ambitious interdisciplinary proposal is to integrate astrophysical models of planetary accretion with geochemical models of planetary differentiation together with cosmochemical constraints obtained from meteorites. The research will involve integrating new models of planetary accretion with core formation models based on the partitioning of a large number of elements between liquid metal and liquid silicate that we will determine experimentally at pressures up to about 100 gigapascals (equivalent to 2400 km deep in the Earth). By comparing our results with the known physical and chemical characteristics of the terrestrial planets, we will obtain a comprehensive understanding of how these planets formed, grew and evolved, both physically and chemically, with time. The integration of chemistry and planetary differentiation with accretion models is a new ground-breaking concept that will lead, through synergies and feedback, to major new advances in the Earth and planetary sciences.
Max ERC Funding
1 826 200 €
Duration
Start date: 2012-05-01, End date: 2018-04-30
Project acronym CelluFuel
Project Designer Cellulosomes by Single Molecule Cut & Paste
Researcher (PI) Hermann Eduard Gaub
Host Institution (HI) LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN
Country Germany
Call Details Advanced Grant (AdG), LS1, ERC-2011-ADG_20110310
Summary Biofuel from wood and waste will be a substantial share of our future energy mix. The conversion of lignocellulose to fermentable polysaccharides is the current bottleneck. We propose to use single molecule cut and paste technology to assemble designer cellulosoms and combine enzymes from different species with nanocatalysts.
Summary
Biofuel from wood and waste will be a substantial share of our future energy mix. The conversion of lignocellulose to fermentable polysaccharides is the current bottleneck. We propose to use single molecule cut and paste technology to assemble designer cellulosoms and combine enzymes from different species with nanocatalysts.
Max ERC Funding
2 351 450 €
Duration
Start date: 2012-03-01, End date: 2018-02-28
Project acronym CLOCKWORKGREEN
Project Ecological performance of arrhythmic plants in nature
Researcher (PI) Ian Thomas Baldwin
Host Institution (HI) Klinik Max Planck Institut für Psychiatrie
Country Germany
Call Details Advanced Grant (AdG), LS8, ERC-2011-ADG_20110310
Summary Timing is everything in ecology, and because plants provide the foundation for most land-based food webs, the timing of their activities profoundly orchestrates the majority of ecological interactions. Most photosynthetic and growth processes are under circadian control, but many additional processes--approximately 30-40% of all genes—are under circadian control, and yet the Darwinian fitness impact of being “in synch” with the environment has not been systematically studied for any organism.
We have developed a toolbox for a native tobacco plant, Nicotiana attenuata, that allows us to “ask the plant” which genes, proteins or metabolites are regulated in particular plant-mediated ecological interactions; identify “the genes that matter” for a given interaction; silence or ectopically express these genes, and conduct field releases with the transformed plants at a nature preserve in the Great Basin Desert to rigorously test hypotheses of gene function. By taking advantage of both our understanding of what it takes for this plant to survive in nature, and the procedures established to disentangle the skein of subtle interactions that determine its performance, we will systematically examine the importance of synchronous entrained endogenous rhythms at all life stages: longevity in the seed bank, germination, rosette growth, elongation, flowering and senescence. Specifically, we propose to silence a key components (starting with NaTOC1) of the plant’s endogenous clock to shorten the plant’s circadian rhythm, both constitutively and with strong dexamethasone-inducible promoters, at all life stages. With a combination of real-time phenotype imaging, metabolite and transcriptome analysis, and ecological know-how, the research will reveal how plants adjust their physiologies to the ever-changing panoply of environmental stresses with which they must cope; by creating arrhythmic plants, we will understand why so many processes are under circadian control.
Summary
Timing is everything in ecology, and because plants provide the foundation for most land-based food webs, the timing of their activities profoundly orchestrates the majority of ecological interactions. Most photosynthetic and growth processes are under circadian control, but many additional processes--approximately 30-40% of all genes—are under circadian control, and yet the Darwinian fitness impact of being “in synch” with the environment has not been systematically studied for any organism.
We have developed a toolbox for a native tobacco plant, Nicotiana attenuata, that allows us to “ask the plant” which genes, proteins or metabolites are regulated in particular plant-mediated ecological interactions; identify “the genes that matter” for a given interaction; silence or ectopically express these genes, and conduct field releases with the transformed plants at a nature preserve in the Great Basin Desert to rigorously test hypotheses of gene function. By taking advantage of both our understanding of what it takes for this plant to survive in nature, and the procedures established to disentangle the skein of subtle interactions that determine its performance, we will systematically examine the importance of synchronous entrained endogenous rhythms at all life stages: longevity in the seed bank, germination, rosette growth, elongation, flowering and senescence. Specifically, we propose to silence a key components (starting with NaTOC1) of the plant’s endogenous clock to shorten the plant’s circadian rhythm, both constitutively and with strong dexamethasone-inducible promoters, at all life stages. With a combination of real-time phenotype imaging, metabolite and transcriptome analysis, and ecological know-how, the research will reveal how plants adjust their physiologies to the ever-changing panoply of environmental stresses with which they must cope; by creating arrhythmic plants, we will understand why so many processes are under circadian control.
Max ERC Funding
2 496 002 €
Duration
Start date: 2012-04-01, End date: 2017-03-31
Project acronym COMPLEX_TRAITS
Project High-throughput dissection of the genetics underlying complex traits
Researcher (PI) Lars Steinmetz
Host Institution (HI) EUROPEAN MOLECULAR BIOLOGY LABORATORY
Country Germany
Call Details Advanced Grant (AdG), LS2, ERC-2011-ADG_20110310
Summary The vast majority of genetic diseases are complex traits, conditioned by multiple genetic and environmental factors. Yet our understanding of the genetics underlying such traits in humans remains extremely limited, due largely to the statistical complexity of inferring the effects of allelic variants in a genetically diverse population. Novel tools for the dissection of the genetic architecture of complex traits, therefore, can be most effectively developed in model organisms, where the contribution of individual alleles can be quantitatively determined in controlled genetic backgrounds. We have previously established the yeast Saccharomyces cerevisiae as a model for complex traits by unravelling complex genetic architectures that govern quantitative phenotypes in this organism. We achieved this by pioneering approaches that have revealed crucial information about the complexity of the underlying genetics. Here we propose to advance to the next level of complex trait dissection by developing systematic, genome-wide technologies that aim to identify all of the variants underlying a complex trait in a single step. In particular, we will investigate traits involved in mitochondrial function, which are both clinically relevant and highly conserved in yeast. Our combination of genomic technologies will allow us to: 1) systematically detect, with maximal sensitivity, the majority of genetic variants (coding and non-coding) that condition these traits; 2) quantify the contributions of these variants and their interactions; and 3) evaluate the strengths and limitations of current methods for dissecting complex traits. Taken together, our research will yield fundamental insights into the genetic complexity of multifactorial traits, providing valuable lessons and establishing novel genomic tools that will facilitate the investigation of complex diseases.
Summary
The vast majority of genetic diseases are complex traits, conditioned by multiple genetic and environmental factors. Yet our understanding of the genetics underlying such traits in humans remains extremely limited, due largely to the statistical complexity of inferring the effects of allelic variants in a genetically diverse population. Novel tools for the dissection of the genetic architecture of complex traits, therefore, can be most effectively developed in model organisms, where the contribution of individual alleles can be quantitatively determined in controlled genetic backgrounds. We have previously established the yeast Saccharomyces cerevisiae as a model for complex traits by unravelling complex genetic architectures that govern quantitative phenotypes in this organism. We achieved this by pioneering approaches that have revealed crucial information about the complexity of the underlying genetics. Here we propose to advance to the next level of complex trait dissection by developing systematic, genome-wide technologies that aim to identify all of the variants underlying a complex trait in a single step. In particular, we will investigate traits involved in mitochondrial function, which are both clinically relevant and highly conserved in yeast. Our combination of genomic technologies will allow us to: 1) systematically detect, with maximal sensitivity, the majority of genetic variants (coding and non-coding) that condition these traits; 2) quantify the contributions of these variants and their interactions; and 3) evaluate the strengths and limitations of current methods for dissecting complex traits. Taken together, our research will yield fundamental insights into the genetic complexity of multifactorial traits, providing valuable lessons and establishing novel genomic tools that will facilitate the investigation of complex diseases.
Max ERC Funding
2 499 821 €
Duration
Start date: 2012-11-01, End date: 2017-10-31
Project acronym Counting conjectures
Project Counting conjectures and characters of almost simple groups
Researcher (PI) Gunter Malle
Host Institution (HI) TECHNISCHE UNIVERSITAT KAISERSLAUTERN
Country Germany
Call Details Advanced Grant (AdG), PE1, ERC-2011-ADG_20110209
Summary This proposal has two major goals: to understand the irreducible complex characters of the finite almost simple groups, and to apply this knowledge to prove two longstanding famous conjectures in the representation theory of finite groups: the McKay conjecture and the Alperin Weight Conjecture.
The first goal requires the study of the action of outer automorphisms of finite groups of Lie type on their irreducible characters and the solution of extension problems. The determination of the irreducible characters of all almost simple groups is a fundamental task of group theory.
For the second goal, we will build on the recent reductions (by the PI and others) of both conjectures to assertions on characters of finite simple groups. To prove these assertions, one needs to construct certain equivariant bijections with respect to outer automorphisms, which will involve the results from the first goal.
Furthermore, we propose to extend the reduction of the McKay conjecture to include several refinements, in particular the block-wise version and
congruences of character degrees.
The project will involve the interplay of methods from the theory of algebraic groups, character sheaves, block theory and modular character theory.
Summary
This proposal has two major goals: to understand the irreducible complex characters of the finite almost simple groups, and to apply this knowledge to prove two longstanding famous conjectures in the representation theory of finite groups: the McKay conjecture and the Alperin Weight Conjecture.
The first goal requires the study of the action of outer automorphisms of finite groups of Lie type on their irreducible characters and the solution of extension problems. The determination of the irreducible characters of all almost simple groups is a fundamental task of group theory.
For the second goal, we will build on the recent reductions (by the PI and others) of both conjectures to assertions on characters of finite simple groups. To prove these assertions, one needs to construct certain equivariant bijections with respect to outer automorphisms, which will involve the results from the first goal.
Furthermore, we propose to extend the reduction of the McKay conjecture to include several refinements, in particular the block-wise version and
congruences of character degrees.
The project will involve the interplay of methods from the theory of algebraic groups, character sheaves, block theory and modular character theory.
Max ERC Funding
1 444 200 €
Duration
Start date: 2012-04-01, End date: 2017-03-31
Project acronym CRYOTRANSLATION
Project High Resolution cryo-EM Analysis of Ribosome-associated Functions
Researcher (PI) Roland Beckmann
Host Institution (HI) LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN
Country Germany
Call Details Advanced Grant (AdG), LS1, ERC-2011-ADG_20110310
Summary "Translation of the genetically encoded information into polypeptides, protein biosynthesis, is a central function executed by ribosomes in all cells. In the case of membrane protein synthesis, integration into the membrane usually occurs co-translationally and requires a ribosome-associated translocon (SecYEG/Sec61). This highly coordinated process is poorly understood, since high-resolution structural information is lacking. Although single particle cryo-electron microscopy (cryo-EM) has given invaluable structural insights for such dynamic ribosomal complexes, the resolution is so far limited to 5-10 Å for asymmetrical particles. Thus, the mechanistic depth and reliability of interpretation has accordingly been limited.
Here, I propose to use single particle cryo-EM at improved, molecular resolution of 3-4 Å to study two fundamental ribosome-associated processes:
(i) co-translational integration of polytopic membrane proteins and
(ii) recycling of the eukaryotic ribosome.
First, we will visualize nascent polytopic membrane proteins inserting into the lipid bilayer via the bacterial ribosome-bound SecYEG translocon. Notably, the translocon will be embedded in a lipid environment provided by so-called nanodiscs. Second, we will visualize in a similar approach membrane protein insertion via the YidC insertase, the main alternative translocon. Third, as a novel research direction, we will determine the structure and function of eukaryotic ribosome recycling complexes involving the ABC-ATPase RLI.
The results will allow, together with functional biochemical data, an in-depth molecular structure-function analysis of these fundamental ribosome-associated processes. Moreover, reaching molecular resolution for asymmetrical particles by single particle cryo-EM will lift this technology to a level of analytical power approaching X-ray and NMR methods. ERC funding would allow for this highly challenging research to be conducted in an internationally competitive way in Europe."
Summary
"Translation of the genetically encoded information into polypeptides, protein biosynthesis, is a central function executed by ribosomes in all cells. In the case of membrane protein synthesis, integration into the membrane usually occurs co-translationally and requires a ribosome-associated translocon (SecYEG/Sec61). This highly coordinated process is poorly understood, since high-resolution structural information is lacking. Although single particle cryo-electron microscopy (cryo-EM) has given invaluable structural insights for such dynamic ribosomal complexes, the resolution is so far limited to 5-10 Å for asymmetrical particles. Thus, the mechanistic depth and reliability of interpretation has accordingly been limited.
Here, I propose to use single particle cryo-EM at improved, molecular resolution of 3-4 Å to study two fundamental ribosome-associated processes:
(i) co-translational integration of polytopic membrane proteins and
(ii) recycling of the eukaryotic ribosome.
First, we will visualize nascent polytopic membrane proteins inserting into the lipid bilayer via the bacterial ribosome-bound SecYEG translocon. Notably, the translocon will be embedded in a lipid environment provided by so-called nanodiscs. Second, we will visualize in a similar approach membrane protein insertion via the YidC insertase, the main alternative translocon. Third, as a novel research direction, we will determine the structure and function of eukaryotic ribosome recycling complexes involving the ABC-ATPase RLI.
The results will allow, together with functional biochemical data, an in-depth molecular structure-function analysis of these fundamental ribosome-associated processes. Moreover, reaching molecular resolution for asymmetrical particles by single particle cryo-EM will lift this technology to a level of analytical power approaching X-ray and NMR methods. ERC funding would allow for this highly challenging research to be conducted in an internationally competitive way in Europe."
Max ERC Funding
2 995 640 €
Duration
Start date: 2012-05-01, End date: 2017-04-30
Project acronym CYTOVOLION
Project Ion homeostasis and volume regulation of cells and organelles
Researcher (PI) Thomas Juergen Jentsch
Host Institution (HI) FORSCHUNGSVERBUND BERLIN EV
Country Germany
Call Details Advanced Grant (AdG), LS4, ERC-2011-ADG_20110310
Summary The regulation of ion concentrations in the cytoplasm and in the lumen of intracellular vesicles provides suitable environments for biochemical reactions, gradients for signal transduction, and generates osmotic gradients for the regulation of the volume of cells and intracellular organelles. Changes in the ion homeostasis and volume of cells and organelles may in turn influence processes like cell division and migration or the budding of vesicles from cellular membranes. Volume changes of cells, and possibly also of intracellular organelles, in turn regulate ion transport across their membranes. Whereas several swelling-activated plasma membrane ion transporters and channels are known, the molecular identity of a key player, the swelling-activated anion channel VRAC, and its impact on cellular functions remain elusive. Only sketchy information is available on ion homeostasis and volume regulation of intracellular organelles like endosomes and lysosomes, in spite of their importance for several diseases.
We propose to perform a genome-wide RNAi screen to finally identify the long-sought swelling-activated Cl- channel VRAC at the molecular level. This screen will also identify genes involved in the regulation of VRAC. The network involved in cell volume regulation will be investigated at the structural, biochemical and cellular level as well as with genetically modified mice. In parallel we will examine the ion homeostasis of endosomes and lysosomes. Until recently only the regulation of luminal H+ and Ca++ concentration was studied, but our recent work demonstrated a crucial role of luminal Cl- and hinted at an important role of cations. A combination of proteomics, siRNA screens, candidate approaches, and mouse models will be used to elucidate the ion homeostasis of endosomes/lysosomes and the impact on organellar function and associated pathologies. We expect that our work will break new ground in ion transport physiology, pathology, and cell biology.
Summary
The regulation of ion concentrations in the cytoplasm and in the lumen of intracellular vesicles provides suitable environments for biochemical reactions, gradients for signal transduction, and generates osmotic gradients for the regulation of the volume of cells and intracellular organelles. Changes in the ion homeostasis and volume of cells and organelles may in turn influence processes like cell division and migration or the budding of vesicles from cellular membranes. Volume changes of cells, and possibly also of intracellular organelles, in turn regulate ion transport across their membranes. Whereas several swelling-activated plasma membrane ion transporters and channels are known, the molecular identity of a key player, the swelling-activated anion channel VRAC, and its impact on cellular functions remain elusive. Only sketchy information is available on ion homeostasis and volume regulation of intracellular organelles like endosomes and lysosomes, in spite of their importance for several diseases.
We propose to perform a genome-wide RNAi screen to finally identify the long-sought swelling-activated Cl- channel VRAC at the molecular level. This screen will also identify genes involved in the regulation of VRAC. The network involved in cell volume regulation will be investigated at the structural, biochemical and cellular level as well as with genetically modified mice. In parallel we will examine the ion homeostasis of endosomes and lysosomes. Until recently only the regulation of luminal H+ and Ca++ concentration was studied, but our recent work demonstrated a crucial role of luminal Cl- and hinted at an important role of cations. A combination of proteomics, siRNA screens, candidate approaches, and mouse models will be used to elucidate the ion homeostasis of endosomes/lysosomes and the impact on organellar function and associated pathologies. We expect that our work will break new ground in ion transport physiology, pathology, and cell biology.
Max ERC Funding
2 499 600 €
Duration
Start date: 2012-04-01, End date: 2017-03-31
Project acronym DEAD2THEEND
Project RNA poly(A) tail: the beginning of the end
Researcher (PI) Elena Conti
Host Institution (HI) Klinik Max Planck Institut für Psychiatrie
Country Germany
Call Details Advanced Grant (AdG), LS1, ERC-2011-ADG_20110310
Summary "The degradation of mature mRNAs has emerged as a key step in the regulation of eukaryotic gene expression. Modulation of the half-life of mRNAs via their degradation is a powerful and versatile mechanism to swiftly alter the expression of proteins in response to changes in physiological conditions. The decay of mRNAs is performed by a set of macromolecular complexes that act in a sequential and coordinated manner, progressively eroding the ends of the transcript until its degradation is complete. These macromolecular assemblies contain only a few catalytically active subunits and a large number of regulatory components. How and why the activities are regulated within the architecture of the complexes is largely unknown. Also unclear are the mechanisms with which the complexes communicate with each other and/or with the changing composition of the nucleic acid. In this project, we will reconstitute the key protein complexes in mRNA decay from recombinant proteins in vitro. Specifically, we will focus on the evolutionary conserved deadenylation, decapping and exosome-Ski complexes. The reconstituted complexes will be used for structural studies to derive atomic models of the holoenzymes using a combination of X-ray crystallography and cryoelectron microscopy. In parallel to obtaining static views of the individual steps in the pathway, we will establish the assays to study how information from one processing step is passed on to the next in a dynamic manner. We will address the basis for the timing and interrelationship of the conserved enzymatic machineries and the influence of the mRNP composition on their activity. Our final goal is to recapitulate the complex behavior of the mRNA decay pathway in vitro. Our lab has extensive experience in biochemical reconstitution of protein complexes, in vitro biochemical assays and X-ray crystallography. In the next five years, we plan to implement cryoelectron microscopy within the scope of this proposal."
Summary
"The degradation of mature mRNAs has emerged as a key step in the regulation of eukaryotic gene expression. Modulation of the half-life of mRNAs via their degradation is a powerful and versatile mechanism to swiftly alter the expression of proteins in response to changes in physiological conditions. The decay of mRNAs is performed by a set of macromolecular complexes that act in a sequential and coordinated manner, progressively eroding the ends of the transcript until its degradation is complete. These macromolecular assemblies contain only a few catalytically active subunits and a large number of regulatory components. How and why the activities are regulated within the architecture of the complexes is largely unknown. Also unclear are the mechanisms with which the complexes communicate with each other and/or with the changing composition of the nucleic acid. In this project, we will reconstitute the key protein complexes in mRNA decay from recombinant proteins in vitro. Specifically, we will focus on the evolutionary conserved deadenylation, decapping and exosome-Ski complexes. The reconstituted complexes will be used for structural studies to derive atomic models of the holoenzymes using a combination of X-ray crystallography and cryoelectron microscopy. In parallel to obtaining static views of the individual steps in the pathway, we will establish the assays to study how information from one processing step is passed on to the next in a dynamic manner. We will address the basis for the timing and interrelationship of the conserved enzymatic machineries and the influence of the mRNP composition on their activity. Our final goal is to recapitulate the complex behavior of the mRNA decay pathway in vitro. Our lab has extensive experience in biochemical reconstitution of protein complexes, in vitro biochemical assays and X-ray crystallography. In the next five years, we plan to implement cryoelectron microscopy within the scope of this proposal."
Max ERC Funding
2 499 344 €
Duration
Start date: 2012-04-01, End date: 2017-03-31
