title: Periplasmic Acid Stress Increases Cell Division Asymmetry (Polar Aging) of Escherichia coli.
abstract: Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed polar aging or cell division asymmetry. It is unknown whether cell division asymmetry can arise from a periplasmic stress, such as the stress of extracellular acid, which is mediated by the periplasm. We tested the effect of periplasmic acid stress on growth and division of adherent single cells. We tracked individual cell lineages over five or more generations, using fluorescence microscopy with ratiometric pHluorin to measure cytoplasmic pH. Adherent colonies were perfused continually with LBK medium buffered at pH 6.00 or at pH 7.50; the external pH determines periplasmic pH. In each experiment, cell lineages were mapped to correlate division time, pole age and cell generation number. In colonies perfused at pH 6.0, the cells inheriting the oldest pole divided significantly more slowly than the cells inheriting the newest pole. In colonies perfused at pH 7.50 (near or above cytoplasmic pH), no significant cell division asymmetry was observed. Under both conditions (periplasmic pH 6.0 or pH 7.5) the cells maintained cytoplasmic pH values at 7.2-7.3. No evidence of cytoplasmic protein aggregation was seen. Thus, periplasmic acid stress leads to cell division asymmetry with minimal cytoplasmic stress.
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Michelle W
authors.initials: MW
authors.lastname: Clark
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Yie
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Eder
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Dennis
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Preston J
authors.initials: PJ
authors.lastname: Basting
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Martinez
authors.affiliation: Department of Mathematics and Statistics, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Jones
authors.affiliation: Department of Biology, Kenyon College, Gambier, Ohio, United States of America.
authors.forename: Joan L
authors.initials: JL
authors.lastname: Slonczewski
mesh_terms: D060049:Asymmetric Cell Division; D004926:Escherichia coli / Q000166:cytology / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019897:Periplasm / Q000378:metabolism*; D066329:Protein Aggregates; D013312:Stress, Physiological
chemical_list: D029968:Escherichia coli Proteins; D066329:Protein Aggregates