Meleah Hickman
I am currently a graduate student in the UPGG program, working with Dr. Laura Rusche. I came to Duke in 2004 from Olympia, Washington where I grew up and went to college at The Evergreen State College. My experience at Evergreen cultivated my interests in molecular evolutionary biology as well as developed my awareness of scientific community. Duke has continued to develop these elements of science in my life.
Promoter-specific repression and regional, long range spreading of silencing factors may seem like two distinct mechanisms for transcriptional gene repression. In Saccharomyces cerevisiae the cryptic mating type loci is subject to long-range silencing mediated by the SIR complex, whereas specific sporulation genes are repressed by the promoter specific SUM1 complex. These complexes utilize the histone deacetylases Sir2p and Hst1p, respectively and are known paralogs originating from an ancient whole-genome duplication. We have investigated the evolution of the HST1-SIR2 duplicate gene pair, and by extension the SIR and SUM1 complexes from two complementary perspectives: the duplicated and non-duplicated contexts by using the model organism S. cerevisiae and the emerging model organism Kluyveromyces lactis, respectively.
We have previously shown that in S. cerevisiae Sir2p can substitute for Hst1p in its absence by interacting with Sum1p, the normal partner of Hst1p. Furthermore, the existence of two distinct protein interaction domains for the Sir and Sum1 complexes was revealed through the analysis of a chimeric Sir2–Hst1 molecule.
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