Analysis of Pseudomonas putida alkane-degradation gene clusters and flanking insertion sequences: evolution and regulation of the alk genes

The Pseudomonas putida GPo1 (commonly known as Pseudomonas oleovorans GPo1) alkBFGHJKL and alkST gene clusters, which encode proteins involved in the conversion of n-alkanes to fatty acids, are located end to end on the OCT p lasmid, separated by 9.7 kb of DNA, This DNA segment encodes, amongst other s, a methyl-accepting transducer protein (AlkN) that may be involved in che motaxis to alkanes. In P, putida P1, the alkBFGHJKL and alkST gene clusters are flanked by almost identical copies of the insertion sequence ISPpu4 co nstituting a class 1 transposon. Other insertion sequences flank and interr upt the alk genes in both strains. Apart from the coding regions of the GPo 1 and P1 alk genes (80-92 % sequence identity), only the alkB and alkS prom oter regions are conserved. Competition experiments suggest that highly con served inverted repeats in the alkS and alkS promoter regions bind AlkS.