This study examined the role of <I>PYKI </I>coding sequences in the expression of <I>PYK1::lacZ </I>gene fusions in <I>Saccharomyces cerevisiae. </I>Further aims were to examine the effects of the vector system upon the mRNA levels from these gene fusions the effect that these gene fusions have upon the yeast cell in general. Analysis of the <I>PYK1::lacZ </I>gene fusions revealed that <I>PYK1 </I>coding sequences were responsible for elevating mRNA levels. This elevation was not due to a single element within the coding region of the <I>PYK1 </I>gene as had been previously proposed (Purvis <I>et al.,</I> 1987a; Lithgow, 1989). Models for the stimulatory action of the <I>PYK1 </I>coding region upon the transcription of the <I>PYK1::lacZ</I> gene fusion were presented. <I>PYKI </I>coding region fragments in the <I>PYK1::lacZ</I> gene fusions stabilized the mRNA, but the data presented here were not consistent with a stability element within the <I>PYK1 </I>coding region. An alternative model was presented whereby the translation rate of the mRNA can influence its decay. The effect of expression of these gene fusions upon the yeast cell in general was monitored by examining the mRNA level of two chromosomal loci, <I>PYK1 </I>and <I>PGK1, </I>and by measuring the generation time. In contrast to previous findings, <I>PYK1 </I>and <I>PGK1 </I>mRNA levels were found not to change and so it was concluded that expression of these gene fusions had no general effect upon transcription or mRNA decay. However expression of these gene fusions did lead to an increase in generation time, and it was proposed that this might be due to a general effect upon translation brought about by a reduction in the intracellular pools of tRNAs for non-preferred codons.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:240970 |
| Date | January 1994 |
| Creators | Wicksteed, Barton |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU068131 |
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