Cross-species chimeras reveal BamA POTRA and β-barrel domains must be fine-tuned for efficient OMP insertion

Abstract

BAM is a conserved molecular machine, the central component of which is BamA. Orthologues of BamA are found in all Gram-negative bacteria, chloroplasts and mitochondria where it is required for the folding and insertion of β-barrel containing integral outer membrane proteins (OMPs) into the outer membrane. BamA binds unfolded β-barrel precursors via the five polypeptide transport-associated (POTRA) domains at its N-terminus. The C-terminus of BamA folds into a β-barrel domain, which tethers BamA to the outer membrane and is involved in OMP insertion. BamA orthologues are found in all Gram-negative bacteria and appear to function in a species-specific manner. Here we investigate the nature of this species-specificity by examining whether chimeric Escherichia coli BamA fusion proteins, carrying either the β-barrel or POTRA domains from various BamA orthologues, can functionally replace E. coli BamA. We demonstrate that the β-barrel domains of many BamA orthologues are functionally interchangeable. We show that defects in the orthologous POTRA domains can be rescued by compensatory mutations within the β-barrel. These data reveal that the POTRA and barrel domains must be precisely aligned to ensure efficient OMP insertion.

Publication DOI: https://doi.org/10.1111/mmi.13052
Divisions: College of Health & Life Sciences > School of Biosciences
Additional Information: © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Funding: Medical Research Council
Uncontrolled Keywords: Bacterial Outer Membrane Proteins/chemistry,Chimera/genetics,Escherichia coli/genetics,Escherichia coli Proteins/chemistry,Gram-Negative Bacteria/genetics,Models, Molecular,Molecular Sequence Data,Protein Conformation,Protein Folding,Protein Structure, Secondary,Protein Structure, Tertiary,Recombinant Fusion Proteins/genetics,Species Specificity
Publication ISSN: 1365-2958
Full Text Link:
Related URLs: https://onlinel ... .1111/mmi.13052 (Publisher URL)
PURE Output Type: Article
Published Date: 2015-08
Authors: Browning, Douglas F (ORCID Profile 0000-0003-4672-3514)
Bavro, Vassiliy N
Mason, Jessica L
Sevastsyanovich, Yanina R
Rossiter, Amanda E
Jeeves, Mark
Wells, Timothy J
Knowles, Timothy J
Cunningham, Adam F
Donald, James W
Palmer, Tracy
Overduin, Michael
Henderson, Ian R

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