Biology subjects

Canas-Duarte, S. J.

Publications and source records attributed to Canas-Duarte, S. J..

2 recordsLinked to original sources

bioRxiv2024

Glycogen phase separation drives macromolecular rearrangement and asymmetric division in E. coli

Bacteria often experience nutrient limitation. While the exponential and stationary growth phases have been characterized in the model bacterium Escherichia coli, little is known about what transpires inside individual cells during the transition between these two phases. Through quantitative cell imaging, we found that the positions of nucleoids and cell division sites become increasingly asymmetric during transition phase. These asymmetries were coupled with asymmetric reorganization of protein, ribosome, and RNA probes in the cytoplasm. Results from live-cell imaging experiments, complemented with genetic and 13C whole-cell nuclear magnetic resonance spectroscopy studies, show that preferential accumulation of the storage polymer glycogen at the old cell pole leads to the observed rearrangements and asymmetric divisions. Live-cell atomic force microscopy analysis, combined with in vitro biochemical experiments, suggests that these phenotypes are due to the propensity of glycogen to phase separate into soft condensates in the crowded cytoplasm. Glycogen-associated differences in cell sizes between strains and future daughter cells suggest that glycogen phase separation allows cells to store large glucose reserves without counting them as cytoplasmic space.

microbiology↗

bioRxiv2020

An integrative approach points to membrane composition as a key factor in E. coli persistence

Many diverse bacteria can enter non- or slow-growing states where they are transiently tolerant to antibiotics. Despite its medical importance, the genetic mechanisms underlying this persistence remain largely unknown, especially for spontaneous (type II) persistence that arise during exponential growth in rich medium. To address this challenge, here we combine genomic, transcriptomic and lipidomic analysis to identify the persistence mechanisms. We first analyzed the genome of the high-persistence mutant Escherichia coli DS1 (hipQ) to identify candidate genes for the high persistence phenotype. We then compared the gene expression profile of spontaneous persisters to normally growing cells with RNAseq and find that the activation of stress response mechanisms is likely not very important in the entrance into hipQ-driven spontaneous persistence. Transcriptomic results also suggest that modifications in the cell membrane play an important role, as further corroborated by lipidomic profiles showing a higher level of unsaturated fatty acids in spontaneous persisters compared to induced persisters or normally growing cells. Taken together, our results indicate that changing membrane composition is a key process in persistence, and further our understanding of spontaneous persister cells from the DS1 (hipQ) context.

microbiology↗