Crystal Structure of β-Barrel Assembly Machinery BamCD Protein Complex

Kim, Kelly H.; Aulakh, Suraaj; Paetzel, Mark

doi:10.1074/jbc.m111.298166

Cited by 75 publications

(92 citation statements)

References 41 publications

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“…Sam35 and BamD share no obvious sequence homology but perform the same receptor-like function in binding unfolded substrates at the surface of the membrane into which those substrates are inserted (21,30); therefore, the conservation of the β-barrel assembly mechanism extends beyond the steps performed by BamA. Previous reports demonstrating that some mitochondrial β-barrels can be assembled in bacteria and that some bacterial OMPs can be assembled in mitochondria implied that the assembly complexes have similar substrate recognition mechanisms (40)(41)(42)(43), and structural studies (13)(14)(15)(44)(45)(46) suggested that BamD might recognize OMP substrates based on its homology to proteins that bind C-terminal peptides (e.g., a component of the mitochondrial translocase, Tom70; a peroxisomal protein receptor, PEX5; and a factor responsible for organizing Hsp chaperone proteins, Hop). Our results connect these observations and provide the underlying molecular basis for substrate recognition, which explains the reciprocity of β-barrel assembly between mitochondria and bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…However, the mechanism by which β-barrel assembly proceeds is only beginning to be elucidated. Structures of the components of the bacterial β-barrel assembly machine (BamA-E) have been determined recently, and several hypotheses about how they facilitate the assembly of its substrates have been proposed (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). The β-barrel component BamA contains a kinked β-strand, which might allow substrate proteins to be inserted by passing laterally from the lumen of the BamA β-barrel into the hydrophobic membrane (18).…”

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confidence: 99%

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Inhibition of the β-barrel assembly machine by a peptide that binds BamD

Hagan

Wzorek

Kahne

2015

Proc. Natl. Acad. Sci. U.S.A.

104

145

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The protein complex that assembles integral membrane β-barrel proteins in the outer membranes of Gram-negative bacteria is an attractive target in the development of new antibiotics. This complex, the β-barrel assembly machine (Bam), contains two essential proteins, BamA and BamD. We have identified a peptide that inhibits the assembly of β-barrel proteins in vitro by characterizing the interaction of BamD with an unfolded substrate protein. This peptide is a fragment of the substrate protein and contains a conserved amino acid sequence. We have demonstrated that mutations of this sequence in the full-length substrate protein impair the protein's assembly, implying that BamD's interaction with this sequence is an important part of the assembly mechanism. Finally, we have found that in vivo expression of a peptide containing this sequence causes growth defects and sensitizes Escherichia coli to antibiotics to which they are normally resistant. Therefore, inhibiting the binding of substrates to BamD is a viable strategy for developing new antibiotics directed against Gram-negative bacteria.β-barrel | outer membrane | protein folding | Bam complex | inhibition

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Inhibition of the β-barrel assembly machine by a peptide that binds BamD

Hagan

Wzorek

Kahne

2015

Proc. Natl. Acad. Sci. U.S.A.

104

145

View full text Add to dashboard Cite

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“…High-resolution structures of all four Bam lipoproteins of E. coli have also been solved (14,16,15,18,25,35). These structures suggest that some of the lipoproteins may also interact with the ␤-barrel OMP substrates (14,15,35), although experimental data supporting this notion are lacking. Unlike BamBCE, BamD is present in almost all members of Proteobacteria and has been shown to be essential in E. coli (21,26) and Neisseria meningitidis (42).…”

mentioning

confidence: 86%

Genetic, Biochemical, and Molecular Characterization of the Polypeptide Transport-Associated Domain of Escherichia coli BamA

et al. 2012

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The BamA protein of Escherichia coli plays a central role in the assembly of ␤-barrel outer membrane proteins (OMPs). The Cterminal domain of BamA folds into an integral outer membrane ␤-barrel, and the N terminus forms a periplasmic polypeptide transport-associated (POTRA) domain for OMP reception and assembly. We show here that BamA misfolding, caused by the deletion of the R44 residue from the ␣2 helix of the POTRA 1 domain (⌬R44), can be overcome by the insertion of alanine 2 residues upstream or downstream from the ⌬R44 site. This highlights the importance of the side chain orientation of the ␣2 helix residues for normal POTRA 1 activity. The ⌬R44-mediated POTRA folding defect and its correction by the insertion of alanine were further demonstrated by using a construct expressing just the soluble POTRA domain. Besides misfolding, the expression of BamA ⌬R44 from a low-copy-number plasmid confers a severe drug hypersensitivity phenotype. A spontaneous drug-resistant revertant of BamA ⌬R44 was found to carry an A18S substitution in the ␣1 helix of POTRA 1. In the BamA ⌬R44, A18S background, OMP biogenesis improved dramatically, and this correlated with improved BamA folding, BamA-SurA interactions, and LptD (lipopolysaccharide transporter) biogenesis. The presence of the A18S substitution in the wild-type BamA protein did not affect the activity of BamA. The discovery of the A18S substitution in the ␣1 helix of the POTRA 1 domain as a suppressor of the folding defect caused by ⌬R44 underscores the importance of the helix 1 and 2 regions in BamA folding.

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“…For example, N. meningitidis appear to lack BamB [72]. Representative structures of all the components of the BAM complex have now been solved and have been instrumental in guiding ongoing research [7][8][9]60,[73][74][75][76][77][78][79][80][81][82] (figure 3).…”

Section: Outer Membrane Protein Delivery To the B-barrel Assembly Macmentioning

confidence: 99%

Outer membrane protein biogenesis in Gram-negative bacteria

Rollauer

Sooreshjani

Noinaj

et al. 2015

Phil. Trans. R. Soc. B

201

178

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Gram-negative bacteria contain a double membrane which serves for both protection and for providing nutrients for viability. The outermost of these membranes is called the outer membrane (OM), and it contains a host of fully integrated membrane proteins which serve essential functions for the cell, including nutrient uptake, cell adhesion, cell signalling and waste export. For pathogenic strains, many of these outer membrane proteins (OMPs) also serve as virulence factors for nutrient scavenging and evasion of host defence mechanisms. OMPs are unique membrane proteins in that they have a β-barrel fold and can range in size from 8 to 26 strands, yet can still serve many different functions for the cell. Despite their essential roles in cell survival and virulence, the exact mechanism for the biogenesis of these OMPs into the OM has remained largely unknown. However, the past decade has witnessed significant progress towards unravelling the pathways and mechanisms necessary for moulding a nascent polypeptide into a functional OMP within the OM. Here, we will review some of these recent discoveries that have advanced our understanding of the biogenesis of OMPs in Gram-negative bacteria, starting with synthesis in the cytoplasm to folding and insertion into the OM.

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Crystal Structure of β-Barrel Assembly Machinery BamCD Protein Complex

Cited by 75 publications

References 41 publications

Inhibition of the β-barrel assembly machine by a peptide that binds BamD

Inhibition of the β-barrel assembly machine by a peptide that binds BamD

Genetic, Biochemical, and Molecular Characterization of the Polypeptide Transport-Associated Domain of Escherichia coli BamA

Outer membrane protein biogenesis in Gram-negative bacteria

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