Wade Hicks | Harvard Medical School (original) (raw)
Address: Boston, Massachusetts, United States
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Institute of Mountain Hazards and Environment, Chinese Academic of Science, Chengdu, 610041, China
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Papers by Wade Hicks
Proceedings of The National Academy of Sciences, 2011
The ability to induce synchronously a single site-specific doublestrand break (DSB) in a budding ... more The ability to induce synchronously a single site-specific doublestrand break (DSB) in a budding yeast chromosome has made it possible to monitor the kinetics and genetic requirements of many molecular steps during DSB repair. Special attention has been paid to the switching of mating-type genes in Saccharomyces cerevisiae, a process initiated by the HO endonuclease by cleaving the MAT locus. A DSB in MATa is repaired by homologous recombinationspecifically, by gene conversion-using a heterochromatic donor, HMLα. Repair results in the replacement of the a-specific sequences (Ya) by Yα and switching from MATa to MATα. We report that MAT switching requires the DNA replication factor Dpb11, although it does not require the Cdc7-Dbf4 kinase or the Mcm and Cdc45 helicase components. Using Southern blot, PCR, and ChIP analysis of samples collected every 10 min, we extend previous studies of this process to identify the times for the loading of Rad51 recombinase protein onto the DSB ends at MAT, the subsequent strand invasion by the Rad51 nucleoprotein filament into the donor sequences, the initiation of new DNA synthesis, and the removal of the nonhomologous Y sequences. In addition we report evidence for the transient displacement of well-positioned nucleosomes in the HML donor locus during strand invasion.
Science, 2010
To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces... more To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces cerevisiae we studied gene conversion in which both strands of DNA are newly synthesized. The mutation rate increases up to 1400 times over spontaneous events, with a significantly different mutation signature. Especially prominent are microhomology-mediated template switches. Recombination-induced mutations are largely independent of mismatch repair, by DNA polymerases Polz, Polh, and Pol32, but result from errors made by Pold and Pole. These observations suggest that increased DSB frequencies in oncogene-activated mammalian cells may also increase the probability of acquiring mutations required for transition to a cancerous state.
Science, 2010
To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces... more To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces cerevisiae we studied gene conversion in which both strands of DNA are newly synthesized. The mutation rate increases up to 1400 times over spontaneous events, with a significantly different mutation signature. Especially prominent are microhomology-mediated template switches. Recombination-induced mutations are largely independent of mismatch repair, by DNA polymerases Polz, Polh, and Pol32, but result from errors made by Pold and Pole. These observations suggest that increased DSB frequencies in oncogene-activated mammalian cells may also increase the probability of acquiring mutations required for transition to a cancerous state.
Proceedings of The National Academy of Sciences, 2011
The ability to induce synchronously a single site-specific doublestrand break (DSB) in a budding ... more The ability to induce synchronously a single site-specific doublestrand break (DSB) in a budding yeast chromosome has made it possible to monitor the kinetics and genetic requirements of many molecular steps during DSB repair. Special attention has been paid to the switching of mating-type genes in Saccharomyces cerevisiae, a process initiated by the HO endonuclease by cleaving the MAT locus. A DSB in MATa is repaired by homologous recombinationspecifically, by gene conversion-using a heterochromatic donor, HMLα. Repair results in the replacement of the a-specific sequences (Ya) by Yα and switching from MATa to MATα. We report that MAT switching requires the DNA replication factor Dpb11, although it does not require the Cdc7-Dbf4 kinase or the Mcm and Cdc45 helicase components. Using Southern blot, PCR, and ChIP analysis of samples collected every 10 min, we extend previous studies of this process to identify the times for the loading of Rad51 recombinase protein onto the DSB ends at MAT, the subsequent strand invasion by the Rad51 nucleoprotein filament into the donor sequences, the initiation of new DNA synthesis, and the removal of the nonhomologous Y sequences. In addition we report evidence for the transient displacement of well-positioned nucleosomes in the HML donor locus during strand invasion.
Science, 2010
To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces... more To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces cerevisiae we studied gene conversion in which both strands of DNA are newly synthesized. The mutation rate increases up to 1400 times over spontaneous events, with a significantly different mutation signature. Especially prominent are microhomology-mediated template switches. Recombination-induced mutations are largely independent of mismatch repair, by DNA polymerases Polz, Polh, and Pol32, but result from errors made by Pold and Pole. These observations suggest that increased DSB frequencies in oncogene-activated mammalian cells may also increase the probability of acquiring mutations required for transition to a cancerous state.
Science, 2010
To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces... more To examine the fidelity of DNA synthesis during double-strand break (DSB) repair in Saccharomyces cerevisiae we studied gene conversion in which both strands of DNA are newly synthesized. The mutation rate increases up to 1400 times over spontaneous events, with a significantly different mutation signature. Especially prominent are microhomology-mediated template switches. Recombination-induced mutations are largely independent of mismatch repair, by DNA polymerases Polz, Polh, and Pol32, but result from errors made by Pold and Pole. These observations suggest that increased DSB frequencies in oncogene-activated mammalian cells may also increase the probability of acquiring mutations required for transition to a cancerous state.