Article ID Journal Published Year Pages File Type
1317575 Journal of Inorganic Biochemistry 2007 12 Pages PDF
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.

Related Topics
Physical Sciences and Engineering Chemistry Inorganic Chemistry
Authors
, , , , ,