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Crystal structure of the virulence factor YopN in complex with its heterodimeric chaperone SycN-YscB
Structural highlights
FunctionYOPN_YERPE Plays a major role in regulation of the low-calcium response. Seems to sense the calcium concentration and to transmit a signal to shut off yop transcription when the calcium concentration is high (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedYersinia pestis, the causative agent of plague, utilizes a type III secretion system (T3SS) to inject effector proteins directly into the cytosol of mammalian cells where they interfere with signal transduction pathways that regulate actin cytoskeleton dynamics and inflammation, thereby enabling the bacterium to avoid engulfment and destruction by macrophages. Type III secretion normally does not occur in the absence of close contact with eukaryotic cells. Negative regulation is mediated in part by a multiprotein complex that has been proposed to act as a physical impediment to type III secretion by blocking the entrance to the secretion apparatus prior to contact with mammalian cells. This complex is composed of YopN, its heterodimeric secretion chaperone SycN-YscB, and TyeA. Here, we report two crystal structures of YopN in complex with its heterodimeric secretion chaperone SycN-YscB and the co-regulatory protein TyeA, respectively. By merging these two overlapping structures, it was possible to construct a credible theoretical model of the YopN-SycN-YscB-TyeA complex. The modeled assembly features the secretion signaling elements of YopN at one end of an elongated structure and the secretion regulating TyeA binding site at the other. A patch of highly conserved residues on the surface of the C-terminal alpha-helix of TyeA may mediate its interaction with structural components of the secretion apparatus. Conserved arginine residues that reside inside a prominent cavity at the dimer interface of SycN-YscB were mutated in order to investigate whether they play a role in targeting the YopN-chaperone complex to the type III secretion apparatus. One of the mutants exhibited a phenotype that is consistent with this hypothesis. Three-dimensional structure of a macromolecular assembly that regulates type III secretion in Yersinia pestis.,Schubot FD, Jackson MW, Penrose KJ, Cherry S, Tropea JE, Plano GV, Waugh DS J Mol Biol. 2005 Mar 4;346(4):1147-61. Epub 2005 Jan 20. PMID:15701523[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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