Reference number : GC-2017-Q1-01984, amendment number : , agreement type : G, recipient legal name : Weber, Stephanie (McGill University)|Weber, Stephanie (Université McGill), recipient country : CA, recipient province : nan, recipient city : Quebec|Québec, recipient postal code : nan, program name english : Discovery Grants Program - Individual, program name french : Programme de subventions à la découverte - individuelles, program purpose english : Living cells are divided into functional compartments called organelles. In eukaryotes, membranes create a diffusion barrier between organelles and the cytoplasm, such that each compartment maintains a distinct biochemical composition that is tailored for its particular function. The biophysical mechanisms underlying the structure and function of membrane-bound organelles are well understood. However, cells also contain organelles that are not enclosed by membranes. For example, stress granules, P bodies and the nucleolus belong to a class of membraneless organelles called "cellular bodies". These bodies consist of local concentrations of proteins and nucleic acids that rapidly exchange with the surrounding cytoplasm or nucleoplasm. Recent evidence suggests that cellular bodies assemble by liquid-liquid phase separation, during which soluble molecules condense from the cytoplasm (or nucleoplasm) to form concentrated liquid-like organelles. My postdoctoral work on the nucleolus, a large cellular body responsible for ribosome biogenesis, was instrumental in defining phase separation as a new mechanism for intracellular organization. 
 
Here, I propose to investigate these concepts in a new biological context: bacteria. Since prokaryotes typically lack membrane-bound organelles, phase separation could provide an alternate mechanism for spatial and functional organization in this domain of life. My lab will explore this idea using transcription foci in E. coli . Transcription foci are clusters of RNA polymerase that appear to be structural and functional analogs of the nucleolus. Therefore, I hypothesize that TF are cellular bodies that (i) assemble by phase separation and (ii) function to accelerate ribosome biogenesis. 
 
To test this hypothesis, we will combine live-cell fluorescence microscopy, quantitative image analysis and physical modeling. The discovery of cellular bodies in prokaryotes will establish a new paradigm for intracellular organization and demonstrate the universality of phase separation as an organizing principle that extends across the entire tree of life., program purpose french : Living cells are divided into functional compartments called organelles. In eukaryotes, membranes create a diffusion barrier between organelles and the cytoplasm, such that each compartment maintains a distinct biochemical composition that is tailored for its particular function. The biophysical mechanisms underlying the structure and function of membrane-bound organelles are well understood. However, cells also contain organelles that are not enclosed by membranes. For example, stress granules, P bodies and the nucleolus belong to a class of membraneless organelles called "cellular bodies". These bodies consist of local concentrations of proteins and nucleic acids that rapidly exchange with the surrounding cytoplasm or nucleoplasm. Recent evidence suggests that cellular bodies assemble by liquid-liquid phase separation, during which soluble molecules condense from the cytoplasm (or nucleoplasm) to form concentrated liquid-like organelles. My postdoctoral work on the nucleolus, a large cellular body responsible for ribosome biogenesis, was instrumental in defining phase separation as a new mechanism for intracellular organization. 
 
Here, I propose to investigate these concepts in a new biological context: bacteria. Since prokaryotes typically lack membrane-bound organelles, phase separation could provide an alternate mechanism for spatial and functional organization in this domain of life. My lab will explore this idea using transcription foci in E. coli . Transcription foci are clusters of RNA polymerase that appear to be structural and functional analogs of the nucleolus. Therefore, I hypothesize that TF are cellular bodies that (i) assemble by phase separation and (ii) function to accelerate ribosome biogenesis. 
 
To test this hypothesis, we will combine live-cell fluorescence microscopy, quantitative image analysis and physical modeling. The discovery of cellular bodies in prokaryotes will establish a new paradigm for intracellular organization and demonstrate the universality of phase separation as an organizing principle that extends across the entire tree of life., agreement title english : Biophysical mechanisms driving spatial organization in bacterial cells, agreement title french : Biophysical mechanisms driving spatial organization in bacterial cells, agreement number : RGPIN, agreement value : 225000.0, agreement start date : 2017-05-10, agreement end date : nan, description english : nan, description french : nan, expected results english : nan, expected results french : nan, additional information english : Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023), additional information french : Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023), owner organization : nserc-crsng, owner organization title : Natural Sciences and Engineering Research Council of Canada | Conseil de recherches en sciences naturelles et en génie du Canada