Control over the mitotic cell division cycle of the fission yeast <I>Schizosaccharomyces pombe</I> is exerted at two main points, mitotic entry and an earlier point, situated prior to DNA replication, known as Start. At Start, cells become committed to one of a number of developmental pathways. The genes <I>cdc2</I><SUP>+</SUP> and <I>cdc10</I><SUP>+</SUP> are both required for commitment to the mitotic pathway. The <I>cdc22</I><SUP>+</SUP> gene encodes an enzyme which functions in S phase, and is periodically expressed at the G1/S boundary. Cdc10 binds elements in the <I>cdc22</I><SUP>+</SUP> promoter known as MCBs, and synthetic MCBs, inserted upstream of a reporter gene, confer periodicity of expression upon it. A second reporter gene has been constructed, under the control of sequences from the <I>cdc22</I><SUP>+</SUP> promoter, and this has been used, together with the MCB-controlled reporter, to investigate the regulation of <I>cdc22</I><SUP>+</SUP> under various conditions of cell cycle arrest. It has been shown that <I>cdc2</I><SUP>+</SUP> is not required at Start for MCB-mediated gene expression. In <I>cdc10</I><SUP>ts</SUP> arrested cells, <I>cdc22</I><SUP>+</SUP>, and the reporter gene under the control of the <I>cdc22</I><SUP>+</SUP> promoter, are both expressed. In contrast, the reporter gene under only MCB control is not expressed independently of <I>cdc10</I><SUP>+</SUP>. This suggests the existence of at least one <I>cis</I>-acting element within the <I>cdc22</I><SUP>+</SUP> promoter, additional to MCBs and required for <I>cdc10</I><SUP>+</SUP>-independent gene expression. The roles of the two clusters of MCBs that are found within the <I>cdc22</I><SUP>+</SUP> promoter have also been investigated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:653337 |
| Date | January 1994 |
| Creators | Kersey, Paul Julian |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15156 |
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