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From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
09:55

From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins

Published on: July 4, 2016

The beta-barrel outer membrane protein assembly complex of Neisseria meningitidis

Elena B Volokhina1, Frank Beckers, Jan Tommassen

  • 1Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.

Journal of Bacteriology
|September 22, 2009
PubMed

Insights

The Neisseria meningitidis beta-barrel assembly machinery (Bam) complex includes Omp85/BamA, RmpM, BamC, ComL/BamD, and BamE. ComL/BamD and BamE are crucial for outer membrane protein assembly and cell viability.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • The Omp85 protein is essential for outer membrane protein (OMP) assembly in gram-negative bacteria.
  • In Escherichia coli, Omp85 (BamA) functions with accessory lipoproteins forming the beta-barrel assembly machinery (Bam) complex.
  • Neisseria meningitidis serves as a model for studying outer membrane biogenesis.

Purpose of the Study:

  • To investigate the composition and function of the Bam complex in Neisseria meningitidis.
  • To identify the accessory proteins involved in OMP assembly in N. meningitidis.
  • To elucidate the roles of individual components in the Omp85-mediated assembly pathway.

Main Methods:

  • Genome sequence analysis to identify homologs of Bam components.
  • Genetic analysis, including mutant construction and phenotypic characterization.
  • Biochemical assays such as copurification and semi-native gel electrophoresis.

Main Results:

  • N. meningitidis possesses homologs of BamC, BamD (ComL), and BamE, but not BamB. A second BamE homolog, Mlp, was identified.
  • ComL/BamD is essential for viability and OMP assembly, while BamE contributes to assembly efficiency and outer membrane integrity.
  • RmpM was identified as a novel component of the Omp85 complex, stabilizing OMP complexes without being essential for folding.

Conclusions:

  • The N. meningitidis Bam complex comprises Omp85/BamA, RmpM, BamC, ComL/BamD, and BamE.
  • ComL/BamD and BamE are critical accessory components for OMP assembly.
  • The findings provide insights into the conserved yet distinct mechanisms of outer membrane biogenesis in gram-negative bacteria.

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