Sequence-specific solution NMR assignments of the β-barrel insertase BamA to monitor its conformational ensemble at the atomic level

Jean-Baptiste Hartmann, Michael Zahn, Irena Matečko Burmann, Stefan Bibow, Sebastian Hiller

Research output: Contribution to journalArticlepeer-review

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.
Original languageEnglish
Pages (from-to)11252-11260
Number of pages9
JournalJournal of the American Chemical Society
Volume140
Issue number36
Early online date20 Aug 2018
DOIs
Publication statusPublished - 12 Sep 2018

Fingerprint

Dive into the research topics of 'Sequence-specific solution NMR assignments of the β-barrel insertase BamA to monitor its conformational ensemble at the atomic level'. Together they form a unique fingerprint.

Cite this