Every cell produced by the bacterial growth and division cycle must have a chromosome to be viable. Partitioning is the process which ensures this. In this work, the polyploid nature of spherical <I>Escherichia coli</I> mutants was utilised to carry out a series of experiments designed to reveal the underlying nature of the partitioning process. The experiments show that partitioning in <I>E.coli</I> is antimitotic, that is, it actively ensures that the inevitable homozygosity of a normally unichromosomal cell is maintained, even when that cell is multichromosomal. That this was shown in spherical cells also reveals that the process is an innate property of the relationship between partitioning and division, rather than a simple consequence of separating two large chromosomes in a narrow, rod-shaped cell. This subtle, but important definition of what the partitioning process actually achieves, should be useful in further characterisation of the mechanisms involved. Grouping of genes of similar function is a common feature of the <I>E.coli</I> chromosome. At least five clusters of genes involved in cell-wall synthesis, cell division and cell shape maintenance have been identified. The <I>mrd</I>-cluster of genes contains three implicated in morphological aspects of peptidoglycan synthesis. The presence of four uncharacterised genes and a portion of unsequenced DNA in the same region, together with proposals that the region could contain more genes involved in cell-morphology, led to the work presented here. Sequencing, followed by computer analysis and molecular-biological and genetic characterisation provided information about the transcriptional organisation of the region and the function of some of the genes. Also a new mutation affecting cell division was identified in an adjacent region of the chromosome.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:640205 |
| Date | January 1994 |
| Creators | Addinall, Stephen G. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/10799 |
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