An increasing appreciation for the role of small RNA regulators prompted us to
investigate the scope of RNA regulation in the bacterium, Streptomyces
coelicolor. Our search revealed an antisense RNA that corresponds to the
upstream region of four genes encoding cell wall cleavage enzymes (cell wall
hydrolases), and a previously uncharacterized population of transfer RNA (tRNA)
cleavage products. Further characterization of the 'tRNAs led to the discovery that
S. coelicolor tRNAs are cleaved into 'tRNA halves' in a developmentally regulated
fashion. All tRNAs seem to be susceptible to tRNA cleavage, although
a bias was detected for tRNAs specifying highly used codons. To date, our work
is the sole description of 'tRNA half production in a bacterium, and recent
studies suggest that it is a widespread phenomenon among eukaryotic organisms. In a separate line of investigation, we noticed that a previous study had
predicted that the genes associated with the antisense RNA are under the control
of a riboswitch- a regulatory RNA element that directly controls gene expression
in response to specific conditions. Our multifaceted characterization of this
system began with the construction and phenotypic analyses of deletion mutant
strains for several of the cell wall hydrolase-encoding genes. We demonstrate that
S. coelicolor cell wall hydrolases are involved in germination, vegetative growth,
and sporulation. Finally, we studied the potential for riboswitch regulation of one
of the cell wall hydrolase-encoding genes, rpfA. RpfA is a resuscitation:
Qromoting factor protein that is important for the revival of dormant bacteria,
including the human pathogen and S. coelicolor relative - Mycobacterium
tuberculosis. Our investigation uncovered evidence suggesting that the riboswitch
region is involved in the regulation of rpfA, and we identified specific conditions
under which it is repressed. This work represents a novel paradigm in the
regulation of cell wall hydrolase expression. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/21136 |
| Date | 04 1900 |
| Creators | Haiser, Henry |
| Contributors | Elliot, Marie, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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