The β-Barrel Outer Membrane Protein Assembly Complex of<i>Neisseria meningitidis</i>

Volokhina, Elena; Beckers, Frank; Tommassen, Jan; Bos, Martine P.

doi:10.1128/jb.00737-09

Cited by 90 publications

(138 citation statements)

References 49 publications

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“…All current models suggest a close vicinity of the PGL to the outer membrane (74,75) and thus, we selected a spacing between the outer membrane and the PGL of~3 nm. This positioning is in agreement with the observed BAM structure when considered in combination with the finding that the BAM components Pal in Caulobacter crescentus (76) and ComL/BamD in Neisseria gonorrheae (77) bind to PG and that PG binding motifs have been identified in Mlp/BamE in N. meningitidis (78).…”

Section: Discussionsupporting

confidence: 90%

Relative Orientation of POTRA Domains from Cyanobacterial Omp85 Studied by Pulsed EPR Spectroscopy

Dastvan

Brouwer

Schuetz

et al. 2016

Biophysical Journal

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Many proteins of the outer membrane of Gram-negative bacteria and of the outer envelope of the endosymbiotically derived organelles mitochondria and plastids have a b-barrel fold. Their insertion is assisted by membrane proteins of the Omp85-TpsB superfamily. These proteins are composed of a C-terminal b-barrel and a different number of N-terminal POTRA domains, three in the case of cyanobacterial Omp85. Based on structural studies of Omp85 proteins, including the five POTRAdomain-containing BamA protein of Escherichia coli, it is predicted that anaP2 and anaP3 bear a fixed orientation, whereas anaP1 and anaP2 are connected via a flexible hinge. We challenged this proposal by investigating the conformational space of the N-terminal POTRA domains of Omp85 from the cyanobacterium Anabaena sp. PCC 7120 using pulsed electron-electron double resonance (PELDOR, or DEER) spectroscopy. The pronounced dipolar oscillations observed for most of the double spinlabeled positions indicate a rather rigid orientation of the POTRA domains in frozen liquid solution. Based on the PELDOR distance data, structure refinement of the POTRA domains was performed taking two different approaches: 1) treating the individual POTRA domains as rigid bodies; and 2) using an all-atom refinement of the structure. Both refinement approaches yielded ensembles of model structures that are more restricted compared to the conformational ensemble obtained by molecular dynamics simulations, with only a slightly different orientation of N-terminal POTRA domains anaP1 and anaP2 compared with the x-ray structure. The results are discussed in the context of the native environment of the POTRA domains in the periplasm.

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Section: Discussionsupporting

confidence: 90%

Relative Orientation of POTRA Domains from Cyanobacterial Omp85 Studied by Pulsed EPR Spectroscopy

Dastvan

Brouwer

Schuetz

et al. 2016

Biophysical Journal

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“…In single bamB, bamC or bamE mutants, one or a few OMPs are incorrectly assembled, while double mutants have more severe OMP assembly defects or are inviable Sklar et al, 2007;Volokhina et al, 2009;Wu et al, 2005). The N. meningitidis BAM complex contains an additional protein, RmpM (Volokhina et al, 2009), which also associates with the porins PorA and PorB and the TonB-dependent receptors TbpA and LbpA (Jansen et al, 2000;Prinz & Tommassen, 2000). Analysis of Neisseria rmpM mutants suggests that this protein stabilizes OMP complexes rather than participating in OMP assembly (Volokhina et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…In E. coli and N. meningitidis, BamA and BamD are essential for viability, and depletion of either one causes several OMPs to accumulate in their unfolded or monomeric forms (Doerrler & Raetz, 2005;Malinverni et al, 2006;Volokhina et al, 2009;Voulhoux et al, 2003;Werner & Misra, 2005). BamB, BamC and BamE are not essential for viability in E. coli (Bouvier et al, 1991;Rolhion et al, 2005;Sklar et al, 2007), and BamB is absent from neisserial genomes (Volokhina et al, 2009). In single bamB, bamC or bamE mutants, one or a few OMPs are incorrectly assembled, while double mutants have more severe OMP assembly defects or are inviable Sklar et al, 2007;Volokhina et al, 2009;Wu et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…BamB, BamC and BamE are not essential for viability in E. coli (Bouvier et al, 1991;Rolhion et al, 2005;Sklar et al, 2007), and BamB is absent from neisserial genomes (Volokhina et al, 2009). In single bamB, bamC or bamE mutants, one or a few OMPs are incorrectly assembled, while double mutants have more severe OMP assembly defects or are inviable Sklar et al, 2007;Volokhina et al, 2009;Wu et al, 2005). The N. meningitidis BAM complex contains an additional protein, RmpM (Volokhina et al, 2009), which also associates with the porins PorA and PorB and the TonB-dependent receptors TbpA and LbpA (Jansen et al, 2000;Prinz & Tommassen, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…The BAM complex contains the essential b-barrel protein BamA (formerly YaeT in E. coli and Omp85 in N. meningitidis) and the lipoproteins BamB (YfgL), BamC (NlpB), BamD (YfiO) and BamE (SmpA) (Sklar et al, 2007;Wu et al, 2005). In E. coli and N. meningitidis, BamA and BamD are essential for viability, and depletion of either one causes several OMPs to accumulate in their unfolded or monomeric forms (Doerrler & Raetz, 2005;Malinverni et al, 2006;Volokhina et al, 2009;Voulhoux et al, 2003;Werner & Misra, 2005). BamB, BamC and BamE are not essential for viability in E. coli (Bouvier et al, 1991;Rolhion et al, 2005;Sklar et al, 2007), and BamB is absent from neisserial genomes (Volokhina et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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The BAM complex subunit BamE (SmpA) is required for membrane integrity, stalk growth and normal levels of outer membrane β-barrel proteins in Caulobacter crescentus

2010

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The outer membrane of Gram-negative bacteria is an essential compartment containing a specific complement of lipids and proteins that constitute a protective, selective permeability barrier. Outer membrane β-barrel proteins are assembled into the membrane by the essential hetero-oligomeric BAM complex, which contains the lipoprotein BamE. We have identified a homologue of BamE, encoded by CC1365, which is located in the outer membrane of the stalked alpha-proteobacterium Caulobacter crescentus. BamE associates with proteins whose homologues in other bacteria are known to participate in outer membrane protein assembly: BamA (CC1915), BamB (CC1653) and BamD (CC1984). Caulobacter cells lacking BamE grow slowly in rich medium and are hypersensitive to anionic detergents, some antibiotics and heat exposure, which suggest that the membrane integrity of the mutant is compromised. Membranes of the ΔbamE mutant have normal amounts of the outer membrane protein RsaF, a TolC homologue, but are deficient in CpaC*, an aggregated form of the outer membrane secretin for type IV pili. ΔbamE membranes also contain greatly reduced amounts of three TonB-dependent receptors that are abundant in wild-type cells. Cells lacking BamE have short stalks and are delayed in stalk outgrowth during the cell cycle. Based on these findings, we propose that Caulobacter BamE participates in the assembly of outer membrane β-barrel proteins, including one or more substrates required for the initiation of stalk biogenesis.

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ATP‐independent assembly machinery of bacterial outer membranes: BAM complex structure and function set the stage for next‐generation therapeutics

George,

Patil,

Mahalakshmi

2024

Protein Science

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Diderm bacteria employ β‐barrel outer membrane proteins (OMPs) as their first line of communication with their environment. These OMPs are assembled efficiently in the asymmetric outer membrane by the β‐Barrel Assembly Machinery (BAM). The multi‐subunit BAM complex comprises the transmembrane OMP BamA as its functional subunit, with associated lipoproteins (e.g., BamB/C/D/E/F, RmpM) varying across phyla and performing different regulatory roles. The ability of BAM complex to recognize and fold OM β‐barrels of diverse sizes, and reproducibly execute their membrane insertion, is independent of electrochemical energy. Recent atomic structures, which captured BAM–substrate complexes, show the assembly function of BamA can be tailored, with different substrate types exhibiting different folding mechanisms. Here, we highlight common and unique features of its interactome. We discuss how this conserved protein complex has evolved the ability to effectively achieve the directed assembly of diverse OMPs of wide‐ranging sizes (8–36 β‐stranded monomers). Additionally, we discuss how darobactin—the first natural membrane protein inhibitor of Gram‐negative bacteria identified in over five decades—selectively targets and specifically inhibits BamA. We conclude by deliberating how a detailed deduction of BAM complex—associated regulation of OMP biogenesis and OM remodeling will open avenues for the identification and development of effective next‐generation therapeutics against Gram‐negative pathogens.

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The β-Barrel Outer Membrane Protein Assembly Complex ofNeisseria meningitidis

Cited by 90 publications

References 49 publications

Relative Orientation of POTRA Domains from Cyanobacterial Omp85 Studied by Pulsed EPR Spectroscopy

Relative Orientation of POTRA Domains from Cyanobacterial Omp85 Studied by Pulsed EPR Spectroscopy

The BAM complex subunit BamE (SmpA) is required for membrane integrity, stalk growth and normal levels of outer membrane β-barrel proteins in Caulobacter crescentus

ATP‐independent assembly machinery of bacterial outer membranes: BAM complex structure and function set the stage for next‐generation therapeutics

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