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bioRxiv · 10.1101/589077

Trans-membrane association of the Sec and BAM complexes for bacterial outer-membrane biogenesis

Alvira-de-Celis, S.·Watkins, D. W.·Troman, L.·Lorriman, J.·Daum, B.·Gold, V. A. M.·Collinson, I.
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Abstract

SUMMARYThe outer-membrane of Gram-negative bacteria is critical for surface adhesion, pathogenicity, antibiotic resistance and survival. The major constituent – hydrophobic β-barrel Outer-Membrane Proteins (OMPs) – are 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 β-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 SurA and BAM through periplasmic domains of SecDF and YidC, ensuring efficient OMP maturation. Our results show the trans-membrane proton-motive-force (PMF) acts at distinct stages of protein secretion: for SecA-driven translocation across the inner-membrane through SecYEG; and to communicate conformational changes via SecDF to the BAM machinery. The latter presumably ensures efficient passage of OMPs. These interactions provide insights of inter-membrane organisation, the importance of which is becoming increasingly apparent.Competing Interest StatementThe authors have declared no competing interest.View Full Text

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Alvira-de-Celis, S., Watkins, D. W., Troman, L., Lorriman, J., Daum, B., Gold, V. A. M., Collinson, I.. 2019-03-27. Trans-membrane association of the Sec and BAM complexes for bacterial outer-membrane biogenesis. https://doi.org/10.1101/589077

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