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

Research output: Contribution to journalArticle

External organisations

  • Lawson Tait Professor of Gynaecological Cancer, School of Cancer Sciences, Vincent Drive, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom. Electronic address: s.t.kehoe@bham.ac.uk.
  • School of Immunity and Infection, Institute of Microbiology and Infection, Biosciences Building, University Road West, University of Birmingham, Birmingham B15 2TT, UK.
  • University of Dundee

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.

Details

Original languageEnglish
Pages (from-to)646–659
JournalMolecular Microbiology
Volume97
Issue number4
Early online date6 Jun 2015
Publication statusPublished - 12 Aug 2015