![]() ![]() The cell envelope encompasses a symmetrical membrane bilayer known as the inner membrane (IM), an aqueous periplasmic space, and a secondary outer membrane (OM) that surrounds the peptidoglycan layer. The cell envelope of Gram-negative bacteria, such as Escherichia coli, provides a formidable barrier that protects the cell from toxic molecules under a wide range of environmental conditions. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. ![]() This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All relevant data are within the manuscript and its Supporting Information files.įunding: This work was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health ( ), grants AI129940, AI138576 and AI150098 to M.S.T. Received: DecemAccepted: FebruPublished: February 28, 2022Ĭopyright: © 2022 Douglass et al. PLoS Genet 18(2):Įditor: Lotte Søgaard-Andersen, Max Planck Institute for Terrestrial Microbiology: Max-Planck-Institut fur terrestrische Mikrobiologie, GERMANY Our results therefore suggest a model in which “AsmA-like” proteins transport GPLs to the OM, and when hindered, changes in cell shape and shedding of excess LPS aids in maintaining OM asymmetry.Ĭitation: Douglass MV, McLean AB, Trent MS (2022) Absence of YhdP, TamB, and YdbH leads to defects in glycerophospholipid transport and cell morphology in Gram-negative bacteria. Moreover, a yhdP, tamB, ydbH triple mutant is synthetically lethal, but if GPL transport is partially restored by overexpression of YhdP, the cell shape adjusts to accommodate increased membrane content as the cell accumulates GPLs in the IM. We also find that yhdP, tamB double mutants shed excess LPS through outer membrane vesicles, presumably to maintain OM homeostasis when normal anterograde GPL transport is disrupted. The absence of the two largest AsmA-like proteins (YhdP and TamB) leads to cell lysis and antibiotic sensitivity, phenotypes that are rescued by reducing LPS synthesis. Here, we report that YhdP and its homologues, TamB and YdbH, members of the “AsmA-like” family, are critical for OM integrity and necessary for proper GPL transport to the OM. ![]() Understanding this aspect of cell envelope biology could provide a foundation for new antibacterial therapies. The biosynthetic pathways of LPS and GPLs are well characterized, but unlike LPS transport, how GPLs are translocated to the OM remains enigmatic. ![]() Maintaining the asymmetric nature and balance of LPS to GPLs in the OM is critical for bacterial viability. The two major constituents of this asymmetric barrier are lipopolysaccharide (LPS) found in the outer leaflet, and glycerophospholipids (GPLs) in the inner leaflet. The outer membrane (OM) of Gram-negative bacteria provides the cell with a formidable barrier that excludes external threats. ![]()
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