Aromatic catabolism by Escherichia coli : cloning and analysis of the 3,4 dihydroxyphenylacetate pathway genes of Escherichia coli C
Escherichia coli C can utilise 3.4-dihydroxyphenylacetate as a carbon and energy source for growth. The biochemical and genetic characterisation of the chromosomally encoded pathway involved is described in this thesis. The structural genes have been cloned and found to lie in two operons, hpcBCDEF and hpcGH, both of which were negatively controlled by the regulatory gene hpcR. There also appeared to be an additional level of control acting in a positive manner, mediated by cAMP. Various subclones isolated in this analysis were useful in the production of pathway intermediates which were identified by a variety of means. The use of the pathway intermediates in the biochemical characterisation of the 3, 4DHPA catabolic pathway has lead to the identification of a novel step. The use of both biochemical and genetic techniques in the analysis of the pathway has enabled a greater understanding of the interacting mechanisms of the pathway.