2vgx

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Revision as of 09:04, 23 January 2008

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spinqualitylabelsall models 2vgx, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF THE YERSINIA ENTEROCOLITICA TYPE III SECRETION TRANSLOCATOR CHAPERONE SYCD

Overview

Many Gram-negative bacteria use a type III secretion (T3S) system to, directly inject effector molecules into eucaryotic cells in order to, establish a symbiotic or pathogenic relationship with their host. The, translocation of many T3S proteins requires specialized chaperones from, the bacterial cytosol. SycD belongs to a class of T3S chaperones that, assists the secretion of pore-forming translocators and, specifically, chaperones the translocators YopB and YopD from enteropathogenic Yersinia, enterocolitica. In addition, SycD is involved in the regulation of, virulence factor biosynthesis and secretion. In this study, we present two, crystal structures of Y. enterocolitica SycD at 1.95 and 2.6 A resolution, the first experimental structures of a T3S class II chaperone specific for, translocators. The fold of SycD is entirely alpha-helical and reveals, three tetratricopeptide repeat-like motifs that had been predicted from, amino acid sequence. In both structures, SycD forms dimers utilizing, residues from the first tetratricopeptide repeat motif. Using, site-directed mutagenesis and size exclusion chromatography, we verified, that SycD forms head-to-head homodimers in solution. Although in both, structures, dimerization largely depends on the same residues, the two, assemblies represent alternative dimers that exhibit different monomer, orientations and overall shape. In these two distinct head-to-head dimers, both the concave and the convex surface of each monomer are accessible for, interactions with the SycD binding partners YopB and YopD. A SycD variant, carrying two point mutations in the dimerization interface is properly, folded but defective in dimerization. Expression of this stable SycD, monomer in Yersinia does not rescue the phenotype of a sycD null mutant, suggesting a physiological relevance of the dimerization interface.

About this Structure

2VGX is a Single protein structure of sequence from Yersinia enterocolitica. Full crystallographic information is available from OCA.

Reference

Structure of the Yersinia enterocolitica type III secretion translocator chaperone SycD., Buttner CR, Sorg I, Cornelis GR, Heinz DW, Niemann HH, J Mol Biol. 2008 Jan 25;375(4):997-1012. Epub 2007 Nov 12. PMID:18054956

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