1im5
From Proteopedia
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Crystal Structure of Pyrazinamidase of Pyrococcus horikoshii in Complex with Zinc
Overview
Bacterial pyrazinamidase (PZAase)/nicotinamidase converts pyrazinamide (PZA) to ammonia and pyrazinoic acid, which is active against Mycobacterium tuberculosis. Loss of PZAase activity is the major mechanism of pyrazinamide-resistance by M. tuberculosis. We have determined the crystal structure of the gene product of Pyrococcus horikoshii 999 (PH999), a PZAase, and its complex with zinc ion by X-ray crystallography. The overall fold of PH999 is similar to that of N-carbamoylsarcosine amidohydrolase (CSHase) of Arthrobacter sp. and YcaC of Escherichia coli, a protein with unknown physiological function. The active site of PH999 was identified by structural features that are also present in the active sites of CSHase and YcaC: a triad (D10, K94, and C133) and a cis-peptide (between V128 and A129). Surprisingly, a metal ion-binding site was revealed in the active site and subsequently confirmed by crystal structure of PH999 in complex with Zn(2+). The roles of the triad, cis-peptide, and metal ion in the catalysis are proposed. Because of extensive homology between PH999 and PZAase of M. tuberculosis (37% sequence identity), the structure of PH999 provides a structural basis for understanding PZA-resistance by M. tuberculosis harboring PZAase mutations.
About this Structure
1IM5 is a Single protein structure of sequence from Pyrococcus horikoshii with as ligand. Active as Nicotinamidase, with EC number 3.5.1.19 Full crystallographic information is available from OCA.
Reference
Crystal structure and mechanism of catalysis of a pyrazinamidase from Pyrococcus horikoshii., Du X, Wang W, Kim R, Yakota H, Nguyen H, Kim SH, Biochemistry. 2001 Nov 27;40(47):14166-72. PMID:11714269
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