The TamB ortholog of Borrelia burgdorferi interacts with the β‐barrel assembly machine (BAM) complex protein BamA. Issue 5 (23rd September 2016)

• Record Type: Journal Article
• Authors: Iqbal, Henna; Kenedy, Melisha R.; Lybecker, Meghan; Akins, Darrin R.
• Is Part Of: Molecular microbiology. Volume 102:Issue 5(2016)
• Page Start: 757
• Page End: 774
• Publication Date: 2016-09-23
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.13492
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: Two outer membrane protein (OMP) transport systems in diderm bacteria assist in assembly and export of OMPs. These two systems are the β‐barrel assembly machine (BAM) complex and the translocation and assembly module (TAM). The BAM complex consists of the OMP component BamA along with several outer membrane associated proteins. The TAM also consists of an OMP, designated TamA, and a single inner membrane (IM) protein, TamB. Together TamA and TamB aid in the secretion of virulence‐associated OMPs. In this study we characterized the hypothetical protein BB0794 in Borrelia burgdorferi . BB0794 contains a conserved DUF490 domain, which is a motif found in all TamB proteins. All spirochetes lack a TamA ortholog, but computational and physicochemical characterization of BB0794 revealed it is a TamB ortholog. Interestingly, BB0794 was observed to interact with BamA and a BB0794 regulatable mutant displayed altered cellular morphology and antibiotic sensitivity. The observation that B. burgdorferi contains a TamB ortholog that interacts with BamA and is required for proper outer membrane biogenesis not only identifies a novel role for TamB‐like proteins, but also may explain why most diderms harbor a TamB‐like protein while only a select group encodes TamA. Abstract : Borrelia burgdorferi encodes a TamB‐like protein. TamB proteins from Proteobacteria interact with TamA to form the translocation and assemble module (TAM). Spirochetes and many other organisms, however, do not contain a TamA protein, although they encode TamB homologs. Here, we show that the TamB homolog from B. burgdorferi interacts with the BamA protein of the β‐barrel assembly machine (BAM) and suggest this may be a common interaction in organisms that lack TamA and a TAM.