| dc.contributor.author | Xu, Qunli. | en_US |
| dc.date.accessioned | 2014-10-21T12:36:57Z | |
| dc.date.available | 1995 | |
| dc.date.issued | 1995 | en_US |
| dc.identifier.other | AAINN05314 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55074 | |
| dc.description | The Cdc68 protein is a global transcription factor in the yeast Saccharomyces cerevisiae. In an effort to gain in-depth understanding of the mechanism by which Cdc68 regulates transcription, a genetic suppressor approach was undertaken. Four suppressor genes were identified in which mutations alleviate the temperature sensitivity caused by the cdc68-1 mutation. My gene cloning and nucleotide sequencing identified two of the suppressor genes as SAN1 and SUG1. The San1 protein was previously uncovered by a genetic interaction with the Sir4 protein, which is itself involved in chromatin-mediated transcriptional repression. The Sug1 protein has been implicated in both transcriptional regulation and in proteolysis. The san1 and sug1 mutant alleles isolated here suppress pleiotropic effects of cdc68-1, but fail to compensate for the complete loss of Cdc68 function, suggesting that suppression is by restoration of Cdc68 activity. Several lines of evidence described here support the notion that both San1 and Sug1 antagonize Cdc68 function at the protein level. Although identified during the same suppressor screening, the San1 and Sug1 proteins apparently have different functions. Furthermore, the inhibitory effects of San1 and Sug1 are additive, suggesting that San1 and Sug1 modulate Cdc68 activity independently, most likely by different mechanisms. | en_US |
| dc.description | Previous studies have raised the possibility that Cdc68 regulates transcription via chromatin. I pursued this line of investigation and uncovered additional links between Cdc68 and proteins known to modulate chromatin configuration. I also found that nucleosome density on plasmid DNA is dependent on Cdc68 activity. These and additional observations are all consistent with the model that the widespread transcriptional effects of Cdc68 are mediated through chromatin. | en_US |
| dc.description | Independently from its effect on Cdc68 activity, the Sug1 protein plays an essential role in mitosis: sug1-26 mutant cells arrest in the G2/M phase of the cell cycle with an undivided nucleus. To find out how Sug1 regulates mitosis, I determined interactions between Sug1 and several known mitotic regulators. Results of this study and of others suggest that Sug1 may mediate a proteolysis pathway that plays a pivotal role in several mitotic events. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1995. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Molecular. | en_US |
| dc.subject | Biology, Genetics. | en_US |
| dc.title | Yeast proteins that modulate Cdc68 transcriptional activity. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
