Modification of the active site of Mycobacterium tuberculosis KatG after disruption of the Met-Tyr-Trp cross-linked adduct

Sofia M. Kapetanaki, Xiangbo Zhao, Shengwei Yu, Richard S. Magliozzo, Johannes P.M. Schelvis

Research output: Contribution to journalArticle

9 Scopus citations

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.

Original languageEnglish
Pages (from-to)422-433
Number of pages12
JournalJournal of Inorganic Biochemistry
Volume101
Issue number3
DOIs
StatePublished - 1 Mar 2007

Keywords

  • Catalase-peroxidase
  • Mycobacterium tuberculosis
  • Resonance Raman
  • Site-directed mutagenesis

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