title: Lateral opening and exit pore formation are required for BamA function.
abstract: The outer membrane of Gram-negative bacteria is replete with a host of β-barrel outer membrane proteins (OMPs). Despite serving a variety of essential functions, including immune response evasion, the exact mechanism of OMP folding and membrane insertion remains largely unclear. The β-barrel assembly machinery complex is required for OMP biogenesis. Crystal structures and molecular dynamics (MD) simulations of the central and essential component, BamA, suggest a mechanism involving lateral opening of its barrel domain. MD simulations reported here reveal an additional feature of BamA: a substrate exit pore positioned above the lateral opening site. Disulfide crosslinks that prevent lateral opening and exit pore formation result in a loss of BamA function, which can be fully rescued by the reductant tris(2-carboxyethyl)phosphine. These data provide strong evidence that lateral opening and exit pore formation are required for BamA function.
authors: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Nicholas
authors: N
authors: Noinaj
authors: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Adam J
authors: AJ
authors: Kuszak
authors: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors: Curtis
authors: C
authors: Balusek
authors: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors: James C
authors: JC
authors: Gumbart
authors: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: skbuchan@helix.nih.gov.
authors: Susan K
authors: SK
authors: Buchanan
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009154:Mutation; D010720:Phosphines / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003432:Cross-Linking Reagents; D004220:Disulfides; D029968:Escherichia coli Proteins; D010720:Phosphines; C503914:BamA protein, E coli; C080938:tris(2-carboxyethyl)phosphine