Program Brochure Text
Richard S. Magliozzo

The research in my laboratory is devoted to study of the structure and function of a bacterial heme enzyme responsible for activation of an old antibiotic still used to treat tuberculosis; and to the study of another bacterial enzyme that catalyzes radical reactions. The first enzyme, catalase-peroxidase (KatG) from Mycobacterium tuberculosis, activates the antibiotic, isoniazid, producing an intermediate that goes on to form a critical inhibitor of another enzymatic reaction, shutting down the bacteria's ability to synthesize molecules needed for its cell wall. The research involves the application of electron paramagnetic resonance spectroscopy (epr), optical, and resonance Raman spectroscopy to study the structure and reaction mechanism of the enzyme. Stopped-flow spectrophotometry is also applied for identification of intermediates and for study of the kinetics of KatG-catalyzed reactions.
The radical enzyme being studied is E. coli pyruvate formate-lyase. This enzyme is induced when the bacteria are deprived of oxygen. It contains an unusual glycyl radical in its active site, which makes it suitable for study using epr spectroscopy. The kinetics of reactions catalyzed by this enzyme and by catalase-peroxidase are analyzed using rapid freeze-quench epr methods in which solutions are mixed and frozen on the millisecond timescale to enable examination of paramagnetic intermediates.
Other projects involve the application of epr spectroscopy to the study of the toxicity in mitochondria of drug molecules and to radical formation in a DNA-cleaving molecule.
 

Recent references:

Zhang, W., Wong, K.K., Magliozzo, R. S., and Kozarich, J. W. "Inactivation of pyruvate formate-lyase by dioxygen: defining the mechanistic interplay of glycine 734 and cysteine 419 by rapid freeze-quench epr." Biochemistry 40: 4123-4130 (2001).

Chouchane, S., Lippai, I., and Magliozzo, R.S. "Catalase-peroxidase (M. tuberculosis KatG) and isoniazid activation." Biochemistry 39: 9975-9983 (2000).

Yu., S., Chouchane, S., and Magliozzo, R.S. "Characterization of the W321F mutant of Mycobacterium tuberculosis catalase-peroxidase KatG." Prot. Sci. (in press).