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To determine whether those genes that were now part of the competence regulon were actually involved in competence and transformation, I had to create strains that had mutations in some of the genes. I created mutants strains of HI0365, HI0366, HI0939 and HI1182/1183, all now known to be targets of competence regulation. I found that HI0365 was not involved but an HI0366 mutant was completely abrogated in its ability to be transformed. However, it could still bind DNA, just not take it into cells. This would imply that perhaps the product of this gene was involved in the process of translocating DNA from the outside to the inside of the cell. In my competence model, it might homologous to the protein labeled "PilT?" I found that like HI0365, the mutant with a mutated HI0939 gene was completely unable to be transformed. Unlike the HI0365 mutant, though, this mutant could not even bind to exogenous DNA. This phenotype, in addition to some analysis of features of the protein, led me to predict that it fills the role of the proteins labelled "other pilins?" in the competence model. Analysis of the mutant with a deleted gene HI1182/HI1183 was not as straightforward. It was only somewhat affected by the deletion of this gene. There could be a lot of reasons for this, the explanation for which could take up many more pages but I'll leave it at that. So in all, I discovered three new members of the competence regulon and proved that genes from two of those operons were essential for the cells to be able to take up DNA and to be transformed by that DNA. Hopefully additional research will help us to determine exactly what these proteins are responsible for during the process of competence. Hence concluded by dissertation work. I hope you enjoyed the lecture! I published the regulation aspects of my dissertation last year in the Journal of Bacteriology (link).
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