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Nat Struct Biol. 2001 Dec;8(12):1031-6.

Structural and biochemical characterization of the type III secretion chaperones CesT and SigE.

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Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver V6T 1Z3, Canada.


Several Gram-negative bacterial pathogens have evolved a type III secretion system to deliver virulence effector proteins directly into eukaryotic cells, a process essential for disease. This specialized secretion process requires customized chaperones specific for particular effector proteins. The crystal structures of the enterohemorrhagic Escherichia coli O157:H7 Tir-specific chaperone CesT and the Salmonella enterica SigD-specific chaperone SigE reveal a common overall fold and formation of homodimers. Site-directed mutagenesis suggests that variable, delocalized hydrophobic surfaces observed on the chaperone homodimers are responsible for specific binding to a particular effector protein. Isothermal titration calorimetry studies of Tir-CesT and enzymatic activity profiles of SigD-SigE indicate that the effector proteins are not globally unfolded in the presence of their cognate chaperones.

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[Indexed for MEDLINE]

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