title: Structural characterization of Escherichia coli BamE, a lipoprotein component of the β-barrel assembly machinery complex.
abstract: In Escherichia coli, the BAM complex catalyzes the essential process of assembling outer membrane proteins (OMPs). This complex consists of five proteins: one membrane-bound protein, BamA, and four lipoproteins, BamB, BamC, BamD, and BamE. Despite their importance in OMP biogenesis, there is currently a lack of functional and structural information on the BAM complex lipoproteins. BamE is the smallest but most conserved lipoprotein in the complex. The structural and dynamic properties of monomeric BamE (residues 21-133) were determined by NMR spectroscopy. The protein folds as two α-helices packed against a three-stranded antiparallel β-sheet. The N-terminal (Ser21-Thr39) and C-terminal (Pro108-Asn113) residues, as well as a β-hairpin loop (Val76-Gln89), are highly flexible on the subnanosecond time scale. BamE expressed and purified from E. coli also exists in a kinetically trapped dimeric state that has dramatically different NMR spectra, and hence structural features, relative to its monomeric form. The functional significance of the BamE dimer remains to be established. Structural comparison to proteins with a similar architecture suggests that BamE may play a role in mediating the association of the BAM complex or with the BAM complex substrates.
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, South Science Building, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6.
authors.forename: Kelly H
authors.initials: KH
authors.lastname: Kim
authors.forename: Hyun-Seo
authors.initials: HS
authors.lastname: Kang
authors.forename: Mark
authors.initials: M
authors.lastname: Okon
authors.forename: Eric
authors.initials: E
authors.lastname: Escobar-Cabrera
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: McIntosh
authors.forename: Mark
authors.initials: M
authors.lastname: Paetzel
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D013499:Surface Properties
chemical_list: D001425:Bacterial Outer Membrane Proteins; C523551:BamE protein, E coli; D029968:Escherichia coli Proteins