4d5b

Crystal structure of CymA from Klebsiella oxytoca

spinqualitylabelsall models 4d5b, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4d5b is a 2 chain structure with sequence from Klebsiella oxytoca. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.702Å Ligands: C8E, GLC, PRD_900015 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q48391_KLEOX Publication Abstract from PubMed The outer membrane (OM) of gram-negative bacteria forms a protective layer around the cell that serves as a permeability barrier to prevent unrestricted access of noxious substances. The permeability barrier of the OM results partly from the limited pore diameters of OM diffusion channels. As a consequence, there is an "OM size-exclusion limit," and the uptake of bulky molecules with molecular masses of more than approximately 600 Da is thought to be mediated by TonB-dependent, active transporters. Intriguingly, the OM protein CymA from Klebsiella oxytoca does not depend on TonB but nevertheless mediates efficient OM passage of cyclodextrins with diameters of up to approximately 15 A. Here we show, by using X-ray crystallography, molecular dynamics simulations, and single-channel electrophysiology, that CymA forms a monomeric 14-stranded beta-barrel with a large pore that is occluded on the periplasmic side by the N-terminal 15 residues of the protein. Representing a previously unidentified paradigm in OM transport, CymA mediates the passive diffusion of bulky molecules via an elegant transport mechanism in which a mobile element formed by the N terminus acts as a ligand-expelled gate to preserve the permeability barrier of the OM. Outer-membrane translocation of bulky small molecules by passive diffusion.,van den Berg B, Prathyusha Bhamidimarri S, Dahyabhai Prajapati J, Kleinekathofer U, Winterhalter M Proc Natl Acad Sci U S A. 2015 May 26. pii: 201424835. PMID:26015567 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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