Contact Us

Mailing address:
Department of Environmental and Molecular Toxicology
Box 7633, NC State University
Raleigh, NC 27695-7633

Shipping address:
Suite 1104, 850 Main Campus Dr.
Raleigh, NC 27606

Phone 919.515.2274
Fax 919.515.7169

Scott D. McCulloch, Ph.D.
Assistant Professor
Department of Environmental and Molecular Toxicology

Phone: 919-513-1214
E-mail: scott_mcculloch@ncsu.edu

Education

BS, Biochemistry, Cal Poly San Luis Obispo
BS, Microbiology, Cal Poly San Luis Obispo
PhD, Toxicology, University of Kentucky
Postdoctoral Fellow, National Institute of Environmental Health Sciences

McCulloch Curriculum Vitae

 

Research Interests

The research interests of the McCulloch laboratory focus on the role of DNA polymerases in mutagenesis, specifically those mutations resulting from exposure to genotoxic insults. There are at least 14 bona fide DNA polymerases in mammalian cells, the majority of which do not currently have well defined roles in vivo . Many of the more recently discovered polymerases have various ‘unusual properties' and are hypothesized to be specifically suited for a variety processes in vivo , including (so far) translesion synthesis, non-homologous end joining, and somatic hypermutation. One polymerase in particular, pol eta , has been strongly implicated as being crucial for preventing mutations by the UV-light induced cis-syn cyclobutane pyrimidine dimer adduct, as evidenced by the extreme sunlight sensitivity displayed by Xeroderma pigmentosum variant patients who lack the polymerase. However, pol eta displays incredibly low fidelity when bypassing this lesion. This has led to the idea that multiple factors are involved in the complete bypass reaction, including but not limited to proofreading, replication accessory proteins, and the mismatch DNA repair pathway.

 



To test one of these hypotheses, the lab has initiated a set of studies aimed at investigating the role of the single stranded binding protein RPA (replication protein A) during bypass of a common oxidative lesion, 8-oxoguanine. Using in-house purified proteins and a set of quantitative biochemical assays, we will measure the fidelity and efficiency of bypass by human polymerase eta . In addition, using the yeast S. cerevisiae as a ‘screening tool', we will investigate protein residues critical for the bypass properties observed. These structure-function studies will give a greater understanding of the translesion synthesis process. The work will serve as a starting point for a larger effort to better understand the effects of protein interactions among the multiple polymerases hypothesized to be involved in the bypass of DNA lesions. Other potential projects in this area involve the other Y-family and putative lesion bypass polymerases (zeta, iota, kappa), Rev1, and the sliding clamp PCNA, among others.

Another series of experiments being initiated seeks to better understand the mechanisms that control the expression of the various DNA polymerases involved in translesion synthesis and mutagenesis. With the large number of polymerases, access to the DNA must be a tightly controlled process. These experiments will use various biochemical and cell biology based experiments aimed at understanding the transcription and protein expression profiles the various polymerases, starting with Rev1 and pol zeta (Rev3/Rev7). One goal of this work is to understand how exposure to DNA damaging agents (such as many environmental pollutants and chemotherapeutic drugs) affects the relative levels of the various polymerases, and what those changes do to the fidelity of DNA replication. Such studies have important implications in both the treatment of existing cancers, as well as in understanding the carcinogenic process.

Selected Publications

  • McCulloch SD, and Kunkel TA (2008) The fidelity of DNA synthesis by eukaryotic replicative and translesion synthesis polymerases. Cell Res 18:148-161.

  • Sakamoto AN, Stone JS, Kissling GE, McCulloch SD, Pavlov YI, and Kunkel TA (2007) Mutator alleles of yeast DNA polymerase zeta. DNA Repair 6:1829-1838.

  • McCulloch SD , Wood A, Garg P, Burgers PM, and Kunkel TA (2007) The effect of replication accessory proteins on the efficiency and fidelity of TT dimer bypass by S. cerevisiae pol eta . Biochemistry 46:8888-8896.
  • Barone F, McCulloch SD , Macpherson P, Maga G, Yamada M, Nohmi T, Minoprio A, Mazzei F, Kunkel TA, Karran P, and Bignami M (2007) Replication of 2-hydroxyadenine-containing DNA and recognition by human MutSalpha . DNA Repair , 6:355-66.
  • McCulloch SD and Kunkel TA (2006) Multiple solutions to inefficient lesion bypass by T7 DNA polymerase. DNA Repair 5:1373-1383.
  • Lin Q, Clark AB , McCulloch SD , Yuan T, Bronson RT, Kunkel TA, and Kucherlapati R (2006) Increased susceptibility to UV-induced skin carcinogenesis in polymerase eta-deficient mice. Cancer Res 66:87-94.
  • McCulloch SD , and Kunkel TA (2006) Measuring the fidelity of translesion synthesis. Methods Enzymol 408:341-355.
  • McCulloch SD , Kokoska RJ, and Kunkel TA (2004) Efficiency, fidelity and enzymatic switching during translesion DNA synthesis. Cell Cycle 3:580-583.
  • McCulloch SD , Kokoska RJ, Chilkova O, Welch CM, Johansson E, Burgers PM, and Kunkel TA (2004) Enzymatic switching for efficient and accurate translesion DNA replication. Nucl Acids Res 32:4665-4675.
  • Wang M, Devereux TR, Vikis HG, McCulloch SD , Holliday W, Anna C, Wang Y, Bebenek K, Kunkel TA, Guan K, and You M (2004) Pol iota is a candidate for the mouse pulmonary adenoma resistance 2 locus, a major modifier of chemically induced lung neoplasia. Cancer Res 64:1924-1931.
  • McCulloch SD , Kokoska RJ, Masutani C, Iwai S, Hanaoka F, and Kunkel TA (2004) Preferential cis-syn thymine dimer bypass by DNA polymerase eta occurs with biased fidelity. Nature 428:97-100.
  • Kokoska RJ, McCulloch SD , and Kunkel TA (2003) The efficiency and specificity of apurinic/apyrimidinic site bypass by human DNA polymerase eta and Sulfolobus solfataricus Dpo4. J Biol Chem 278:50537-50545.
  • Glick E, Chau J, Vigna K, McCulloch S , Adman E, Kunkel TA, and Loeb L (2003) Amino acid substitutions at conserved tyrosine 52 alter fidelity and bypass efficiency of human DNA polymerase eta . J Biol Chem 278:19341–19346.