Formation of a β-barrel membrane protein is catalyzed by the interior surface of the assembly machine protein BamA
Year: 2019
Type: article
Abstract: The β-barrel assembly machine (Bam) complex in Gram-negative bacteria and its counterparts in mitochondria and chloroplasts fold and insert outer membrane β-barrel proteins. BamA, an essential component of the complex, is itself a β-barrel and is proposed to play a central role in assembling other barrel substrates. Here, we map the path of substrate insertion by the Bam complex using site-specific crosslinking to understand the molecular mechanisms that control β-barrel folding and release. We find that the C-terminal strand of the substrate is stably held by BamA and that the N-terminal strands of the substrate are assembled inside the BamA β-barrel. Importantly, we identify contacts between the assembling β-sheet and the BamA interior surface that determine the rate of substrate folding. Our results support a model in which the interior wall of BamA acts as a chaperone to catalyze β-barrel assembly.
Source: eLife
DOI: 10.7554/elife.49787
Institution: Harvard University
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,500
OpenAlex ID: W2983772074