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Structural basis for chitin acquisition by marine Vibrio species

DOI: 10.1038/s41467-017-02523-y DOI Help

Authors: Anuwat Aunkham (Suranaree University of Technology) , Michael Zahn (Newcastle University) , Anusha Kesireddy (Jacobs University Bremen) , Karunakar Reddy Pothula (Jacobs University Bremen) , Albert Schulte (Vidyasirimedhi Institute of Science and Technology (VISTEC)) , Arnaud Basle (Newcastle University) , Ulrich Kleinekathöfer (Jacobs University Bremen) , Wipa Suginta (Suranaree University of Technology) , Bert Van Den Berg (Newcastle University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 9

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

Open Access Open Access

Abstract: Chitin, an insoluble polymer of N-acetylglucosamine, is one of the most abundant biopolymers on Earth. By degrading chitin, chitinolytic bacteria such as Vibrio harveyi are critical for chitin recycling and maintenance of carbon and nitrogen cycles in the world’s oceans. A decisive step in chitin degradation is the uptake of chito-oligosaccharides by an outer membrane protein channel named chitoporin (ChiP). Here, we report X-ray crystal structures of ChiP from V. harveyi in the presence and absence of chito-oligosaccharides. Structures without bound sugar reveal a trimeric assembly with an unprecedented closing of the transport pore by the N-terminus of a neighboring subunit. Substrate binding ejects the pore plug to open the transport channel. Together with molecular dynamics simulations, electrophysiology and in vitro transport assays our data provide an explanation for the exceptional affinity of ChiP for chito-oligosaccharides and point to an important role of the N-terminal gate in substrate transport.

Journal Keywords: Bacterial structural biology; Carbohydrates; Permeation and transport; X-ray crystallography

Subject Areas: Biology and Bio-materials

Instruments: I02-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I04-Macromolecular Crystallography