Helical shape of Helicobacter pylori requires an atypical glutamine as a zinc ligand in the carboxypeptidase Csd4.

Autor:	Chan AC; From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada., Blair KM; the Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, the Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, and., Liu Y; the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada., Frirdich E; From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada., Gaynor EC; From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada., Tanner ME; the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada., Salama NR; the Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, the Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, and., Murphy ME; From the Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada, michael.murphy@ubc.ca.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2015 Feb 06; Vol. 290 (6), pp. 3622-38. Date of Electronic Publication: 2014 Dec 12.
DOI:	10.1074/jbc.M114.624734
Abstrakt:	Peptidoglycan modifying carboxypeptidases (CPs) are important determinants of bacterial cell shape. Here, we report crystal structures of Csd4, a three-domain protein from the human gastric pathogen Helicobacter pylori. The catalytic zinc in Csd4 is coordinated by a rare His-Glu-Gln configuration that is conserved among most Csd4 homologs, which form a distinct subfamily of CPs. Substitution of the glutamine to histidine, the residue found in prototypical zinc carboxypeptidases, resulted in decreased enzyme activity and inhibition by phosphate. Expression of the histidine variant at the native locus in a H. pylori csd4 deletion strain did not restore the wild-type helical morphology. Biochemical assays show that Csd4 can cleave a tripeptide peptidoglycan substrate analog to release m-DAP. Structures of Csd4 with this substrate analog or product bound at the active site reveal determinants of peptidoglycan specificity and the mechanism to cleave an isopeptide bond to release m-DAP. Our data suggest that Csd4 is the archetype of a new CP subfamily with a domain scheme that differs from this large family of peptide-cleaving enzymes. (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
Databáze:	MEDLINE
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