Role of alternative processivity clap ß*: Interactions with UmuD

CHED 217

Michael J. Ordazzo, ordazzo.m@neu.edu, Bilyana Koleva, Thomas E. Wales, Christopher Morgan, John R. Engen, and Penny J. Beuning. Department of Chemistry and Chemical Biology, Northeastern Univeristy, 360 huntington ave, 102 hurtig hall, Boston, MA 02115
The ß subunit of DNA polymerase III holoenzyme of E. coli is a sliding clamp whose function is to tether the polymerase to the DNA allowing DNA to be replicated with high processivity. It has been shown that UV irradiation of E. coli induces a smaller form of the ß subunit termed ß* that plays a role in increasing resistance to UV irradiation. It was found previously that ß interacts with UmuD and we have found that ß* also interacts with UmuD, a protein involved in UV-induced mutagenesis as well as a primitive DNA damage checkpoint. These findings suggest a role for ß* in recovery from UV damage by involvement in DNA repair or reactivation of DNA replication. In order to determine the role of ß* in DNA damage tolerance, we are probing its interactions with UmuD using several biophysical techniques, including FRET and mass spectrometry.