Physical structure and expression of alkBA encoding alkane hydroxylase and rubredoxin reductase from Pseudomonas maltophilia

The structural genes of the Pseudomonas maltophilia alk system, which are localized on the OCT plasmid were cloned as a 4.2-kilobase pair Hind III fragment. This fragment contains sequences for alkane hydroxylase gene (alkB) and rubredoxin reductase gene (alkA), respectively. The alkB gene encodes a 373-amino acid polypeptide (47.4 kD) that can be expressed at high levels in Pseudomonas and Escherichia coli. The alkBA genes were complemented with alkane hydroxylation in both bacteria. This result shows that alkBA gene is essential for alkane hydroxylation since chromosomal loci have been encoded for other enzymes involved in fatty acid oxidation.