The WD40 Protein BamB Mediates Coupling of BAM Complexes into Assembly Precincts in the Bacterial Outer Membrane

Sachith D Gunasinghe; Takuya Shiota; Christopher J Stubenrauch; Keith E Schulze; Chaille T Webb; Alex J Fulcher; Rhys A Dunstan; Iain D Hay; Thomas Naderer; Donna R Whelan; Toby D M Bell; Kirstin D Elgass; Richard A Strugnell; Trevor Lithgow

doi:10.1016/j.celrep.2018.04.093

The WD40 Protein BamB Mediates Coupling of BAM Complexes into Assembly Precincts in the Bacterial Outer Membrane

Cell Rep. 2018 May 29;23(9):2782-2794. doi: 10.1016/j.celrep.2018.04.093.

Affiliations

¹ Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
² Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia; Organization for Promotion of Tenure Track, University of Miyazaki, Miyazaki 889-1692, Japan.
³ Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia.
⁴ Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia; Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia; Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
⁵ Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
⁶ School of Chemistry, Monash University, Clayton, VIC 3800, Australia; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
⁷ School of Chemistry, Monash University, Clayton, VIC 3800, Australia.
⁸ Monash Micro Imaging, Monash University, Clayton, VIC 3800, Australia; Hudson Institute of Medical Research, Clayton, VIC 3800, Australia.
⁹ Department of Microbiology & Immunology, University of Melbourne, Parkville, VIC 3052, Australia.
¹⁰ Infection & Immunity Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia. Electronic address: trevor.lithgow@monash.edu.

PMID: 29847806
DOI: 10.1016/j.celrep.2018.04.093

Abstract

The β-barrel assembly machinery (BAM) complex is essential for localization of surface proteins on bacterial cells, but the mechanism by which it functions is unclear. We developed a direct stochastic optical reconstruction microscopy (dSTORM) methodology to view the BAM complex in situ. Single-cell analysis showed that discrete membrane precincts housing several BAM complexes are distributed across the E. coli surface, with a nearest neighbor distance of ∼200 nm. The auxiliary lipoprotein subunit BamB was crucial for this spatial distribution, and in situ crosslinking shows that BamB makes intimate contacts with BamA and BamB in neighboring BAM complexes within the precinct. The BAM complex precincts swell when outer membrane protein synthesis is maximal, visual proof that the precincts are active in protein assembly. This nanoscale interrogation of the BAM complex in situ suggests a model whereby bacterial outer membranes contain highly organized assembly precincts to drive integral protein assembly.

Keywords: beta-barrel assembly; membrane domains; membrane proteins; membrane super-complexes; outer membrane biogenesis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacterial Outer Membrane Proteins / chemistry
Bacterial Outer Membrane Proteins / metabolism*
Cell Membrane / metabolism*
Detergents / pharmacology
Escherichia coli / metabolism*
Escherichia coli Proteins / chemistry
Escherichia coli Proteins / metabolism*
Multiprotein Complexes / metabolism*
Protein Biosynthesis / drug effects
Protein Multimerization
Protein Structure, Secondary

Substances

Bacterial Outer Membrane Proteins
BamB protein, E coli
Detergents
Escherichia coli Proteins
Multiprotein Complexes