Monday, 23 May 2005

This presentation is part of: Spectroscopy of Biomolecules Posters

Resonance Raman investigation of the structural/functional role of the unusual adduct in Mycobacterium tuberculosis catalase-peroxidase KatG

Sofia M. Kapetanaki1, Xiangbo Zhao2, Richard S. Magliozzo2, and Johannes P. M. Schelvis1. (1) New York University, New York, NY, (2) Brooklyn College and the Graduate Center of the City University of New York, New York, NY

Mycobacterium tuberculosis (Mtb) KatG is a catalase-peroxidase that is believed to activate the antituberculosis drug, isoniazid (INH). The X-ray crystal structure of Mtb. KatG has revealed an unusual three-amino acid adduct involving the covalently linked distal side tryptophan (W107), tyrosine (Y229), and methionine (M255) residues. Previous studies have shown that KatG(Y229F) has a decreased catalase activity and forms Compound II without detectable accumulation of Compound I, in contrast to the WT enzyme. In order to understand the functional/structural role of this adduct, the local environment of KatG(Y229F) is investigated by resonance Raman spectroscopy, using the exogenous ligands CO and NO. Moreover, the catalytic mechanism of KatG(Y229) is studied. The implications of these findings for the structural/functional role of the adduct and the catalytic mechanism of WT KatG are discussed.

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