Adaptation of the periplasm to maintain spatial constraints essential for cell envelope processes and cell viability

eLife

Eli J Cohen¹  Morgan Beeby¹  Pankaj Deo²  Christopher J Stubenrauch²  Trevor Lithgow²  Eric Mandela²  Von L Torres²  Chaille T Webb²  David Ryoo³  Cheng Huang⁴  Ralf B Schittenhelm⁴  Iain D Hay⁵  Hyea Hwang⁶  JC Gumbart⁷ 

[1] Department of Life Sciences, Imperial College London, London, United Kingdom;Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Australia;Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, United States;Monash Proteomics & Metabolomics Facility, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Australia;School of Biological Sciences, The University of Auckland, Auckland, New Zealand;School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, United States;School of Physics, Georgia Institute of Technology, Atlanta, United States;

关键词: periplasm;    cell envelope;    Lpp;    peptidoglycan;    E. coli;   

DOI  :  10.7554/eLife.73516

来源: eLife Sciences Publications, Ltd

【 摘 要 】

The cell envelope of Gram-negative bacteria consists of two membranes surrounding a periplasm and peptidoglycan layer. Molecular machines spanning the cell envelope depend on spatial constraints and load-bearing forces across the cell envelope and surface. The mechanisms dictating spatial constraints across the cell envelope remain incompletely defined. In Escherichia coli, the coiled-coil lipoprotein Lpp contributes the only covalent linkage between the outer membrane and the underlying peptidoglycan layer. Using proteomics, molecular dynamics, and a synthetic lethal screen, we show that lengthening Lpp to the upper limit does not change the spatial constraint but is accommodated by other factors which thereby become essential for viability. Our findings demonstrate E. coli expressing elongated Lpp does not simply enlarge the periplasm in response, but the bacteria accommodate by a combination of tilting Lpp and reducing the amount of the covalent bridge. By genetic screening, we identified all of the genes in E. coli that become essential in order to enact this adaptation, and by quantitative proteomics discovered that very few proteins need to be up- or down-regulated in steady-state levels in order to accommodate the longer Lpp. We observed increased levels of factors determining cell stiffness, a decrease in membrane integrity, an increased membrane vesiculation and a dependance on otherwise non-essential tethers to maintain lipid transport and peptidoglycan biosynthesis. Further this has implications for understanding how spatial constraint across the envelope controls processes such as flagellum-driven motility, cellular signaling, and protein translocation

【 授权许可】

CC BY