Luis Ortiz-Rodriguez (University of Michigan)

Date: Wed. November 20th, 2024, 4:30 pm-5:30 pm
Location: Clapp 108

Biomolecular Condensation Enables Material State Changes that Dynamically Regulate RNA Metabolism 

Recently, biomolecular condensates have emerged as a broadly utilized mechanism for organizing biochemical pathways within cells, and this organizational paradigm is particularly important within bacteria because these organisms generally lack membrane-bound organelles. Bacterial ribonucleoprotein bodies (BR-bodies) are dynamic biomolecular condensates that play a pivotal role in bacterial RNA metabolism. In this talk, I will demonstrate how BR-bodies orchestrate mRNA decay and storage based on a multidisciplinary approach that combines single-molecule fluorescence microscopy, bulk imaging techniques, biochemical assays, and rigorous quantitative analyses. During exponential growth, BR-bodies act as fluid-like condensates that enhance mRNA decay. This function pivots under stress conditions, during which BR-bodies transition into more solid-like states, becoming reservoirs that store mRNA. This shift is characterized by slowed internal dynamics, increased molecular density, and prolonged residence time of ribonuclease E. Our investigations also show that ATP levels and translation rates drive these changes, suggesting that mRNA accumulation of ribosome-free mRNA is a key factor driving these material state transitions. Moreover, I will demonstrate that, upon nutrient replenishment, stationary-phase BR-bodies disassemble, releasing stored mRNAs for rapid translation and demonstrating that BR-body function is governed by a reversible mechanism for resource management. These findings reveal adaptive strategies by which bacteria regulate RNA metabolism through condensate-mediated control of mRNA decay and storage.