The Pseudomonas oleovorans alkane hydroxylase gene. Sequence and expression.

We have identified and sequenced the Pseudomonas OCT plasmid-encoded alkane hydroxylase gene (alkB) and its promoter. The transcription initiation site of the alkBAC mRNA was determined by nuclease S1 mapping. A putative interaction site with RNA-polymerase was identified based on homology of the alk promoter with other Pseudomonas promoters. The alkB gene encodes a 401-amino acid polypeptide which, despite an unusual codon composition, can be expressed at high levels in Escherichia coli and Pseudomonas. The amino-terminal sequence of the purified cytoplasmic membrane alkane hydroxylase was determined and was found to be in agreement with the nucleotide sequence. The translation product of the alkB gene contains nine hydrophobic sequences of which eight are sufficiently long to be membrane-spanning segments. The amino-terminal sequence resembles that of several bacterial integral membrane proteins and is not cleaved off following translation.