Download MendeleyCrystal structure and mechanism of catalysis of a pyrazinamidase from Pyrococcus horikoshii.
Du, X., Wang, W., Kim, R., Yakota, H., Nguyen, H., Kim, S.H.(2001) Biochemistry 40: 14166-14172
- PubMed: 11714269
- DOI: https://doi.org/10.1021/bi0115479
- Primary Citation of Related Structures:
1ILW, 1IM5 - PubMed Abstract:
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.
Organizational Affiliation:
Department of Chemistry, University of California, Berkeley 94720, USA.
