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Craig Howell

Mentor: Todd Washington, Ph.D.
Lab Phone: 335-7501

DNA polymerase ζ (pol ζ) is a DNA damage bypass polymerase. Replicative polymerases stall at sites of DNA damage, known as lesions, due to distortion of the double helix. Specialized polymerases, however, have evolved which are capable of incorporating nucleotides across from lesions. DNA polymerase has the unique ability to extend from a nucleotide that has been incorporated across from a lesion. The structure of bacteriophage Rb69 DNA polymerase in a ternary complex with dNTP and DNA substrates, as well as sequence alignments of other pola-like polymerases has allowed the identification of 6 highly conserved residues that likely interact with the incoming nucleotide and 6 residues that likely interact with the DNA substrate. Steady state kinetic experiments utilizing site-directed mutants will allow a better understanding of the contribution of each of these residues to the unique properties of pol ζ. Genetic studies where mutant pol ζ is used to complement pol ζ knockout yeast will allow us to understand the physiological significance of each mutant and to correlate phenotype severity with polymerase activity versus wild type.

Howell CA, Kondratick CM, Washington MT. Substitution of a residue contacting the triphosphate moiety of the incoming nucleotide increases the fidelity of yeast DNA polymerase zeta. Nucleic Acids Res. 2008 Mar;36(5):1731-40. Epub 2008 Feb 7. PubMed PMID: 18263611; PubMed Central PMCID: PMC2275142.

Howell CA, Prakash S, Washington MT. Pre-steady-state kinetic studies of protein-template-directed nucleotide incorporation by the yeast Rev1 protein. Biochemistry. 2007 Nov 20;46(46):13451-9. Epub 2007 Oct 26. PubMed PMID:17960914.