Michael E. Harris, Ph.D.

Associate Professor

Center for RNA molecular Biology /
Department of Biochemistry

Research:
Molecular recognition and catalysis by the ribonuclease P: A ribonucleoprotein enzyme.

RNase P is a ribonucleoprotein enzyme with a catalytic RNA subunit that depends on a small protein cofactor for molecular recognition. Thus, it serves as a facile model system to explore fundamental aspects of molecular recognition, RNA-protein interactions and RNA-metal ion interactions. We are pursuing these lines of investigation using the standard physical and spectroscopic tools as well as developing new approaches including collaborative efforts at application of kinetic isotope effects (with Vernon Anderson) and Raman spectroscopy (with Paul Carey).

Analysis of phosphoryl transfer mechanisms using kinetic isotope effects.

Two of the fundamental questions for both RNA and protein enzymes that catalyze phosphoryl transfer are “What is the mechanism of the reaction?” and “How do active site functional groups influence the chemical bonding of the substrate to achieve catalysis?” Both the chemical mechanism and active site interactions influence the bonding environment of the atoms undergoing reaction, which can be assessed by measuring the effects of isotopic substitution at these positions. An important outgrowth of our collaborative studies of ribozyme catalysis has been the development of methods to determine isotope effects for enzymatic and non-enzymatic phosphoryl transfer reactions involving RNA. These studies promise to provide important new information on the mechanism of RNA catalyzed reactions and tests of current hypotheses concerning the role of specific active site interactions.

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Selected Publications

Zahler, N.H., Sun, L., Christian, E.L. and Harris, M.E. (2005).
The Pre-tRNA Nucleotide Base and 2'-Hydroxyl at N(-1) Contribute to Fidelity in tRNA Processing by RNase P.
J. Molec. Biol. 345(5):969-85.

Cassano, A.G., Anderson, V.E. and Harris, M.E. (2004).
Analysis of solvent nucleophile isotope effects: Evidence for concerted mechanisms and nucleophilic activation by metal ion coordination in non-enzymatic and ribozyme catalyzed phosphodiester hydrolysis.
Biochemistry. 43(32):10547-59.

Harris, M.E. and Christian E.L. (2003).
Recent insights into the structure and function of the ribonucleoprotein enzyme RNase P.
Curr. Op. Struct. Biol. 13, 325-333.

Christian, E. L., Kaye, N. M. and Harris, M. E. (2002).
Evidence for a polynuclear metal ion binding site in the catalytic domain of ribonuclease P RNA.
EMBO J 21, 2253-2262.

Cassano, A.G., Anderson, V.E. and Harris, M.E. (2002).
Direct attack by hydroxide in phosphodiester hydrolysis.
J. Am. Chem. Soc. 124(37):10964-5.

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