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Crystal structure of the Acinetobacter baumannii outer membrane protein Omp33

DOI: 10.1107/S205979831800904X DOI Help

Authors: Javier Abellon-ruiz (Newcastle University) , Michael Zahn (Newcastle University) , Arnaud Basle (Newcastle University) , Bert Van Den Berg (Newcastle University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Crystallographica Section D Structural Biology , VOL 74 , PAGES 852 - 860

State: Published (Approved)
Published: September 2018
Diamond Proposal Number(s): 9948

Abstract: Acinetobacter baumannii is becoming a major threat to human health due to its multidrug resistance. This is owing in a large part to the low permeability of its outer membrane (OM), which prevents high internal antibiotic concentrations and makes antibiotic-resistance mechanisms more effective. To exploit OM channels as potential delivery vehicles for future antibiotics, structural information is required. One abundant OM protein in A. baumannii is Omp33. This protein has been reported to be important for the in vivo fitness and virulence of A. baumannii, but its structure is not known. Here, the X-ray crystal structure of Omp33 is reported at a resolution of 2.1 Å. Omp33 has a 14-β-stranded barrel without stable extracellular loop constrictions. Instead, an extended and unusual periplasmic turn connecting β-strands 2 and 3 is present, which folds into the pore lumen and completely blocks the aqueous channel. The Omp33 structure helps in understanding how A. baumannii OM proteins contribute to the low permeability of the cell envelope of this bacterium and suggests that Omp33 might function as a gated channel.

Journal Keywords: outer membrane proteins; Omp33; β-barrel; Acinetobacter baumannii; membrane transport; antibiotics

Subject Areas: Biology and Bio-materials

Instruments: I03-Macromolecular Crystallography , I24-Microfocus Macromolecular Crystallography