Abstracts


Short talk 1: Glycogen phase separation drives macromolecular rearrangement and asymmetric division in Escherichia coli

Silvia J. Canas-Duarte

HHMI/Stanford University, ChEM-H, Biology, 290 Jane Stanford Way, 94305 Stanford [US], sjcd15@stanford.edu

Authors:
Silvia J. Canas-Duarte, Yashna Thappeta, Haozhen Wang, Till Kallem, Alessio Fragasso, Yingjie Xiang, William Gray, Cheyenne Lee, Lynette Cegelski, Christine Jacobs-Wagner

Despite decades of study into E. coli, little is known about the processes that allow it to traverse the transition between exponential growth and the nutriend limited stationary phase. Using quantitative microscopy we found significant changes in the cytoplasmic localization of all major intracellular macromolecules in this ‘transition’. We identified the accumulation of glycogen as the driver of the observed macromolecular rearrangements and the resultant onset of asymmetric divisions in the transition phase. Glycogen was recently shown to undergo LLPS in eukaryotic cells and in vitro, but its accumulation in bacteria has long been described as the formation of granules. Thus, we set to explore the likelihood and consequences of glycogen forming phase-separated condensates in the cytoplasm of E. coli. We found that glycogen undergoes phase transitions in conditions resembling the bacterial cytoplasm. In vivo, our data suggests that glycogen accumulation alters the organization of intracellular components, likely by forming condensates capable of selectively excluding macromolecules. AFM measures in live cells indicate that glycogen condensates are “soft” in nature, compared to the significantly “hard” inclusion bodies measured under the same conditions. Finally, we found that glycogen phase separation likely results in cytoplasmic space compensation, which would allow cells to accumulate this glucose polymer in large amounts without affecting macromolecular homeostasis

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