The methylation of DNA is a widespread phenomenon found in organisms ranging from bacteria to mammals. Methylation of cytosine at the 5-position is the most common form of this modification and is catalyzed by a conserved family of enzymes. In bacteria, methylation of DNA forms part of the restricted-modification system. The role of DNA methylation in eukaryotes is less clearly defined but it has been implicated in process such as the control of gene expression and the organization of chromatin structure. Progress in the understanding of DNA methylation could be greatly enhanced by the opportunity to study this phenomenon in genetically tractable organisms such as yeasts and <I>Drosophila. </I>However, to date, 5-methylcytosine has not been detected in the DNA of these organisms. The fission yeast gene <I>cnd1 </I>(completion of nuclear division) was cloned by complementation of a temperature sensitive mutation and was found to encode a protein with striking homology to cytosine-specific DNA methyltransferase enzymes (m5C-MTases), (R. Bartlett, PhD thesis, Oxford University, 1991). This finding suggested that it might now be possible to study methylation in yeast. Also cloned at this time was an extragenic suppressor of the <I>cnd1-1</I> mutant. In current work, a more detailed methylation analysis of the fission yeast gnome has been carried out. However, it has still not been possible to detect 5-methylcytosine in fission yeast DNA. The extragenic suppressor of the <I>cnd1-1</I> mutant has been sequenced and found to encode a small polypeptide with no homology to known proteins. The m5C-MTase homologue was histidine-tagged, overexpressed in <I>E. coli</I> and purified over a nickel agarose column.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:663789 |
| Date | January 1994 |
| Creators | Wilkinson, Caroline R. M. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11573 |
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