Modification of the Active Site of Mycobacterium Tuberculosis Katg After Disruption of the Met-tyr-trp Cross-linked Adduct.
From: Department of Chemistry, New York University, 100 Washington Square East, Room 1001, New York, NY 10003, USA.
Journal of inorganic biochemistry
- Publish Date: Mar 2007
- ISSN: 0162-0134
- Volume: 101
- Issue: 3
- Pages: 422-33
- Medium: Print
- Language: English
- Citation (JAMA): Kapetanaki Sofia M, Zhao Xiangbo, Yu Shengwei, et al. Modification of the Active Site of Mycobacterium Tuberculosis Katg After Disruption of the Met-tyr-trp Cross-linked Adduct.. J. Inorg. Biochem. Mar 2007;101:422-33
Abstract
Mycobacterium tuberculosis catalase-peroxidase (Mtb KatG) is a bifunctional enzyme that possesses both catalase and peroxidase activities and is responsible for the activation of the antituberculosis drug isoniazid. Mtb KatG contains an unusual adduct in its distal heme-pocket that consists of the covalently linked Trp107, Tyr229, and Met255. The KatG(Y229F) mutant lacks this adduct and has decreased steady-state catalase activity and enhanced peroxidase activity. In order to test a potential structural role of the adduct that supports catalase activity, we have used resonance Raman spectroscopy to probe the local heme environment of KatG(Y229F). In comparison to wild-type KatG, resting KatG(Y229F) contains a significant amount of 6-coordinate, low-spin heme and a more planar heme. Resonance Raman spectroscopy of the ferrous-CO complex of KatG(Y229F) suggest a non-linear Fe-CO binding geometry that is less tilted than in wild-type KatG. These data provide evidence that the Met-Tyr-Trp adduct imparts structural stability to the active site of KatG that seems to be important for sustaining catalase activity.
Mesh Headings (Keywords): Amino Acid Substitution, Antitubercular Agents, Bacterial Proteins, Binding Sites, Catalase, Cross-Linking Reagents, Electron Spin Resonance Spectroscopy, Isoniazid, Mutagenesis, Site-Directed, Mycobacterium tuberculosis, Peroxidases, Phenylalanine, Protein Conformation, Recombinant Proteins, Spectrum Analysis, Raman, Tyrosine
Check for Full Text / PubMed Unique Identifier (PMID): 17188362
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