Inter-membrane association of the Sec and BAM translocons for bacterial outer-membrane biogenesis

Sara Alvira-De-Celis, Dan W Watkins, Lucy A Troman, William J Allen, James Lorriman, Vicki A M Gold, Ian R Collinson*, et al.

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

The outer-membrane of Gram-negative bacteria is critical for surface adhesion, pathogenicity, antibiotic resistance and survival. The major constituent – hydrophobic b-barrel Outer-Membrane Proteins (OMPs) – are first secreted across the inner-membrane through the Sec-translocon for delivery to periplasmic chaperones e.g. SurA, which prevent aggregation. OMPs are then offloaded to the b-Barrel Assembly Machinery (BAM) in the outer-membrane for insertion and folding. We show the Holo-TransLocon (HTL) – an assembly of the protein-channel core-complex SecYEG, the ancillary sub-complex SecDF, and the membrane 'insertase' YidC – contacts BAM through periplasmic domains of SecDF and YidC, ensuring efficient OMP maturation. Furthermore, the proton-motive-force (PMF) across the inner-membrane acts at distinct stages of protein secretion: (1) SecA-driven translocation through SecYEG; and (2) communication of conformational changes via SecDF across the periplasm to BAM. The latter presumably drives efficient passage of OMPs. These interactions provide insights of inter-membrane organisation and communication, the importance of which is becoming increasingly apparent.
Original languageEnglish
Article numbere60669
Number of pages24
JournaleLife
Volume9
Early online date27 Nov 2020
DOIs
Publication statusE-pub ahead of print - 27 Nov 2020

Structured keywords

  • Bristol BioDesign Institute

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