Mechanisms of DNA polymerase-catalyzed bypass of N2-(7,8,9,10-tetrahydrobenzo[a]pyren-10-yl)-2'-deoxyguanosine

TOXI 135

A. S. Prakasha Gowda, pas44@psu.edu1, Lindsey R. DeCarlo1, Jacek Krzeminski, juk15@psu.edu2, Shantu Amin, sga3@psu.edu3, Zucai Suo, suo.3@osu.edu4, and Thomas E. Spratt, tes13@psu.edu5. (1) Department of Biochemistry and Molecular Biology, Pennsylvania State University, H171, 500 University Dr, Hershey, PA 17033, (2) Department of Pharmacology, Pennsylvania State University, 500 University Dr, Hershey, PA 17033, (3) Department of Pharmacology, Penn State College of Medicine, 500 University Dr, Hershey, PA 17033, (4) Department of Biochemistry, The Ohio State University, 484 West 12th Ave., Columbus, OH OH 43210, (5) Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Room C5711B Mail Code H171, 500 University Drive, Hershey, PA 17033
A major factor in the carcinogenicity of benzo[a]pyrene (BP) is believed to be the error prone bypass of N2-(7,8,9,10-tetrahydrobenzo[a]pyren-10-yl)-2'-deoxyguanosine ([BP]G) by Y-family polymerases. We probed the base pair structures that occur during Dpo4 catalyzed translesion synthesis kinetically using nucleotide analogs in which potential hydrogen bonds were disrupted by N to CH substitutions. Our results are consistent with purine/purine mispair formation that occurs via a Hoogsteen base pair in which the template purine nucleotide is in the syn-conformation while the dNTP is in the anti-conformation. Our results indicate that the incorporation of dATP and dGTP opposite [BP]G occur with different mechanisms. The 100-fold decrease in rate for the incorporation of 7-deaza-dATP, relative to dATP, supports a dATP(syn)/[BP]G(anti) Hoogsteen base pair. The results with dGTP analogs are consistent with the reversed dGTP(anti)/[BP]G(syn) geometry.
 

General Papers
1:00 PM-4:45 PM, Wednesday, August 22, 2007 BCEC -- 258C, Oral

Division of Chemical Toxicology

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007