Gene redundancy of two-component (chloro)phenol hydroxylases in Rhodococcus opacus 1CP

Among other factors, a distinct gene redundancy is discussed to facilitate high metabolic versatility of rhodococci. Rhodococcus opacus 1CP is a typical member in that respect and degrades a multitude of (chlorinated) aromatic compounds. In contrast to the central pathways of aromatic degradation in strain 1CP, little is known about the degree of gene redundancy and to what extent this is reflected on protein level within the steps of peripheral degradation. By means of degenerated primers deduced from tryptic peptides of a purified phenol hydroxylase component and using the amplified fragment as a labelled probe against genomic 1CP-DNA, three gene sets encoding three different two-component phenol hydroxylases pheA1/pheA2(1-3) could be identified. One of them was found to be located on the megaplasmid p1CP, which confirms the role of these elements for metabolic versatility. Protein chromatography of phenol- and 4-chlorophenol-grown 1CP-biomass gave first evidences on a functional expression of these oxygenases, which could be initially characterised in respect of their substrate specificity.