Department of Biochemistry
School of Medicine & Biomedical Sciences
Faculty

   JENNIFER A. SURTEES, Ph.D.
   Assistant Professor

   email: jsurtees@buffalo.edu

We are interested in the fundamental question of genome stability.  In particular, we are interested in the mechanisms by which mismatch repair (MMR) proteins find, recognize and bind their DNA substrates and how these interactions target the DNA for different types of repair.  Understanding these mechanisms is extremely interesting from a basic mechanistic point of view, but also has important implications for human disease.  MMR defects cause genetic instability in general, and have been associated with hereditary non-polyposis colorectal cancer (HNPCC) as well as a number of sporadic cancers.  HNPCC is a major human cancer syndrome, accounting for ~ 5% of all colorectal cancers as well as cancers of the stomach, small intestine, ovary and endometrium.  More recently, MMR factors have been implicated in trinucleotide repeat disorders (e.g. Huntington disease) and immunoglobulin gene rearrangements in B-cell development.
     
DNA mismatch repair (MMR) proteins detect and eliminate errors that occur during DNA replication.  In eukaryotes, two distinct heterodimeric complexes, MSH2-MSH3 and MSH2-MSH6, are each involved in mismatch recognition.  MSH2-MSH3 recognizes small loops of 1-16 nucleotides in length, while MSH2-MSH6 primarily recognizes mispairs and single nucleotide loops.  Both complexes have ATPase activity, which is critical for regulating downstream repair events.   Once a MSH complex is bound to the mispaired DNA, a MutL homolog, MLH1-PMS1 in yeast, is recruited to initiate subsequent repair steps. 

Figure 1. MSH proteins recognize and bind misrepairs. Downstream factors are then recruited to complete repair

MSH proteins are also involved in the repair or resolution of a number of DNA structures.  For example, genetic studies have shown that MSH2-MSH3, along with the RAD1-RAD10 endonuclease, is required for a subset of double-strand break repair (DSBR) pathways in which a DNA intermediate with 3’ non-homologous tails is generated, e.g. single-strand annealing (SSA).  SSA is a major DSBR pathway in mammalian cells.  Therefore understanding the mechanism of this process is critical, as its failure can lead to significant genome instability in vivo.

Figure 2. MSH2-MSH3 binds both misrepair substrates (insertion loops and bubbles) and recombination intermediates with similar affinity. MSH2-MSH3 is required for the resolution of both types of DNA intermediates in vivo.

We use Saccharomyces cerevisiae as a model organism to study the MMR proteins.  These proteins and repair processes are highly conserved in eukaryotes; therefore studies in yeast are widely applicable throughout evolution.  Yeast provides powerful classical biochemical and genetic techniques to probe the protein-protein and protein-DNA interactions involved in DNA repair.  In addition, we will apply novel single molecule and proteomic/mass spectrometry approaches to the following key question questions:

1. How do MSH complexes locate DNA substrates within and outside the context of the replication fork?
2. Do MSH complexes differ in their binding to DNA to generate substrate specificity? 
3. How are MSH-DNA complexes channeled into different DNA repair/resolution pathways?
4. How does genetic background affect genome stability and carcinogenesis?

Selected Recent Publications:

Xu, X., Page, J.L., Surtees, J.A., Liu, H., Bronson R., Alani, E., Nikitin, A.Y. and Weiss, R.S. (2008)  Broad overexpression of ribonucleotide reductase genes in mice specifically induces lung neoplasms.  Cancer Res. In press.
 
Gorman, J., Chowdhury, A., Surtees, J.A., Shimuda, J., Reichman, D.R., Alani, E. and Greene E.C. (2007) Dynamic basis for one-dimensional DNA scanning by the mismatch repair complex Msh2-Msh6. Mol. Cell 28:359-370. [PDF]

Lee, S.D.*, Surtees, J.A.*, and Alani, E. (2007) S. cerevisiae MSH2-MSH3 and MSH2-MSH6 complexes display distinct requirements for mismatch recognition Domain I in DNA repair.  J. Mol. Biol. 366:53-66. [PDF]
* equal authorship

Surtees, J.A. and Alani, E. (2006) Mismatch repair factor MSH2-MSH3 binds and alters the conformation of branched DNA structures predicted to form during genetic recombination.  J. Mol. Biol. 360:523-536. [PDF]

Jiang, J., Bai, L., Surtees, J.A., Gemici, Z., Wang, M.D. and Alani, E. (2005) Detection of high affinity mismatch binding and sliding clamp modes for the MSH2-MSH6 mismatch recognition complex by single-molecule unzipping force analysis.  Mol. Cell.  20:771-781. [PDF]

Surtees, J.A., Argueso, J.L. and Alani, E. (2004) Mismatch repair proteins: Key regulators of genetic recombination.  Cytogenet Genome Res (Special Issue on “Repair Proteins in Meiosis”) 107:146-159.

Surtees, J.A. and Alani, E. (2004) Replication factors license exonuclease I in mismatch repair. Mol. Cell 15:164-166.