Immobile lipopolysaccharides and outer membrane proteins differentially segregate in growing Escherichia coli

• 成果类型: Article
• 署名作者: Kumar, Sandip; Inns, Patrick G.; Ward, Scott; Lagage, Valentine; Wang, Jingyu; Kaminska, Renata; Booth, Martin J.; Uphoff, Stephan; Cohen, Edward A. K.; Mamou, Gideon; Kleanthous, Colin
• 署名单位: University of Oxford; Imperial College London; University of Oxford; Hebrew University of Jerusalem
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8999
• DOI: 10.1073/pnas.2414725122
• 发表日期: 2025-03-11
• 关键词: salmonella-typhimurium; molecular-basis; surface; ompf

摘要

The outer membrane (OM) of gram-negative bacteria is a robust, impermeable barrier that excludes many classes of antibiotics. Contrary to the classical model of an asymmetric lipid bilayer, recent evidence suggests the OM is predominantly an asymmetric integral beta-barrel outer membrane proteins (OMPs) are shared with other OMPs to form a supramolecular network in which the levels of OMPs approach those of LPS. Some of the most abundant OMPs in the Escherichia coli OM are trimeric porins. How porins and LPS are incorporated into the OM of growing bacteria is poorly understood. Here, we use live-cell imaging and microfluidics to investigate how LPS, labeled using click chemistry, and the porin OmpF, labeled using the bacteriocin colicin N, are incorporated into the E. coli OM. Diffraction-limited fluorescence microscopy shows OmpF and LPS to be uniformly distributed and immobile. However, clustering of both macromolecules becomes evident by superresolution microscopy, which is also the case for their biogenesis proteins, BamA and LptD, respectively. Notwithstanding these common organizational features, OmpF insertion into the OM is cell-cycle-dependent leading to binary partitioning and strong polar accumulation of old OmpF. Old LPS on the other hand is diluted similar to 50% at each division cycle by new LPS, resulting in only mild polar accumulation of preexisting LPS. We conclude that although LPS and OMPs are destined to form the APLM their insertion dynamics are fundamentally different, which has major implications for understanding how the OM is assembled.