PDBsum entry 6fsu

Membrane protein

PDB id: 6fsu

Contents

Protein chains

388 a.a.

Waters ×53

References listed in PDB file

Key reference

• Title: Sequence-Specific solution nmr assignments of the β-Barrel insertase bama to monitor its conformational ensemble at the atomic level.
• Authors: J.B.Hartmann, M.Zahn, I.M.Burmann, S.Bibow, S.Hiller.
• Ref.: J Am Chem Soc, 2018, 140, 11252-11260. [DOI no: 10.1021/jacs.8b03220]
• PubMed id: 30125090

Abstract

β-barrel outer membrane proteins (Omps) are key functional components of the outer membranes of Gram-negative bacteria, mitochondria, and plastids. In bacteria, their biogenesis requires the β-barrel-assembly machinery (Bam) with the central insertase BamA, but the exact translocation and insertion mechanism remains elusive. The BamA insertase features a loosely closed gating region between the first and last β-strand 16. Here, we describe ∼70% complete sequence-specific NMR resonance assignments of the transmembrane region of the BamA β-barrel in detergent micelles. On the basis of the assignments, NMR spectra show that the BamA barrel populates a conformational ensemble in slow exchange equilibrium, both in detergent micelles and lipid bilayer nanodiscs. Individual conformers can be selected from the ensemble by the introduction of a C-terminal strand extension, single-point mutations, or specific disulfide cross-linkings, and these modifications at the barrel seam are found to be allosterically coupled to sites at the entire barrel circumference. The resonance assignment provides a platform for mechanistic studies of BamA at atomic resolution, as well as for investigating interactions with potential antibiotic drugs and partner proteins.