Research Summary:

Prof. Williams' main research interest is the biophysics of DNA-protein interactions. DNA is normally found as a double helix consisting of a sequence of base pairs, representing the genetic code. In order for this code to be read to create proteins (transcription and translation) or to make copies of the DNA (replication), the two strands of the double helix must be separated to expose the bases. The processes of replication and transcription are regulated by proteins that bind to DNA and alter the stability of the double helix. In his research Prof. Williams uses optical tweezers instruments to apply very small forces to single DNA molecules. Measurement of these forces allows him to determine the stability of the DNA double helix and the extent to which various DNA binding proteins alter the structure and stability of DNA. This approach provides unique insights into the function of these proteins in the cell.

Recent Publications:

Jingyun Zhang, Micah J. McCauley, L. James Maher, III, Mark C. Williams, and N. E. Israeloff. Mechanism of DNA flexibility enhancement by HMGB proteins. Nucleic Acids Research 37: 1107-1114 (2009).

Micah J. McCauley and Mark C. Williams. Optical Tweezers Experiments Resolve Distinct Modes of DNA-Protein Binding. Biopolymers 91: 265-282 (2009).

Kristen M. Stewart-Maynard, Margareta Cruceanu, Fei Wang, My-Nuong Vo, Robert J. Gorelick, Mark C. Williams, Ioulia Rouzina, and Karin Musier-Forsyth. Retroviral Nucleocapsid Proteins Display Non-equivalent Levels of Nucleic Acid Chaperone Activity. Journal of Virology 82: 10129-10142 (2008).

Micah J. McCauley, Leila Shokri, Jana Sefcikova, Česlovas Venclovas, Penny J. Beuning, and Mark C.Williams. Distinct Double- and Single-Stranded DNA Binding of E. coli Replicative DNA Polymerase III Alpha Subunit. ACS Chemical Biology 3: 577-587 (2008). This work was also featured in a journal podcast.

Leila Shokri, Micah J. McCauley, Ioulia Rouzina, and Mark C. Williams. DNA overstretching in the presence of glyoxal: Structural evidence of force-induced DNA melting. Biophysical Journal 95: 1248-1255 (2008).

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