title: BamA POTRA Domain Interacts with a Native Lipid Membrane Surface.
abstract: The outer membrane of Gram-negative bacteria is an asymmetric membrane with lipopolysaccharides on the external leaflet and phospholipids on the periplasmic leaflet. This outer membrane contains mainly β-barrel transmembrane proteins and lipidated periplasmic proteins (lipoproteins). The multisubunit protein β-barrel assembly machine (BAM) catalyzes the insertion and folding of the β-barrel proteins into this membrane. In Escherichia coli, the BAM complex consists of five subunits, a core transmembrane β-barrel with a long periplasmic domain (BamA) and four lipoproteins (BamB/C/D/E). The BamA periplasmic domain is composed of five globular subdomains in tandem called POTRA motifs that are key to BAM complex formation and interaction with the substrate β-barrel proteins. The BAM complex is believed to undergo conformational cycling while facilitating insertion of client proteins into the outer membrane. Reports describing variable conformations and dynamics of the periplasmic POTRA domain have been published. Therefore, elucidation of the conformational dynamics of the POTRA domain in full-length BamA is important to understand the function of this molecular complex. Using molecular dynamics simulations, we present evidence that the conformational flexibility of the POTRA domain is modulated by binding to the periplasmic surface of a native lipid membrane. Furthermore, membrane binding of the POTRA domain is compatible with both BamB and BamD binding, suggesting that conformational selection of different POTRA domain conformations may be involved in the mechanism of BAM-facilitated insertion of outer membrane β-barrel proteins.
authors.affiliation: T. C. Jenkins Department of Biophysics, John Hopkins University, Baltimore, Maryland.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Fleming
authors.affiliation: Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
authors.forename: Dhilon S
authors.initials: DS
authors.lastname: Patel
authors.affiliation: Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
authors.forename: Emilia L
authors.initials: EL
authors.lastname: Wu
authors.affiliation: Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Qi
authors.affiliation: Korean Institute of Science and Technology Information, Yuseong-gu, Daejeon, Korea.
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Yeom
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado.
authors.forename: Marcelo Carlos
authors.initials: MC
authors.lastname: Sousa
authors.affiliation: T. C. Jenkins Department of Biophysics, John Hopkins University, Baltimore, Maryland.
authors.forename: Karen G
authors.initials: KG
authors.lastname: Fleming
authors.affiliation: Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas. Electronic address: wonpil@ku.edu.
authors.forename: Wonpil
authors.initials: W
authors.lastname: Im
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004548:Elasticity; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D000072417:Protein Domains; D055503:Protein Multimerization; D014867:Water / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; C503914:BamA protein, E coli; C557407:BamB protein, E coli; C513739:BamD protein, E coli; D029968:Escherichia coli Proteins; D014867:Water