Cloning of an ORF with homology to Mycobacterium echA1, encoding the enoyl-CoA hydratase, in Rhodococcus fascians.

An open reading frame encoding a polypeptide of significant homology (55.7% identity) with the enoyl-CoA hydratase encoded by the gene echA1 from Mycobacterium tuberculosis has been found in the genome of the plant-pathogen bacteria Rhodococcus fascians strain NRRL-B-15096. Sequence alignments showed that it possesses several conserved blocks common to E. coli, M. tuberculosis and human mitochondria. One of such blocks includes a glutamate residue located at position 149, corresponding to the glutamate 139 of Escherichia coli. This glutamate was previously shown to be the catalytic residue of enoyl-CoA hydratase in the multienzyme complex of fatty acid oxidation from E. coli. Our results provide additional information on the conserved domains of this enzyme. Significant homologies in other genome regions between R. fascians and M. tuberculosis confirm their phylogenetic relationship.