Characterization of IS2112, a new insertion sequence from Rhodococcus, andits relationship with mobile elements belonging to the IS110 family

A new insertion sequence (IS2112) was identified in the genome of the 1-hal oalkane-utilizing bacterium Rhodococcus rhodochrous NCIMB 13064. The insert ion element is 1415 bp long, does not contain terminal inverted repeats, an d is not flanked by directly repeated sequences. IS2112 belongs to the IS11 0 family of transposable elements, and forms a separate subfamily, along wi th IS116, Two copies of IS2112 were found in R, rhodochrous NCIMB 13064 and one, two or three copies of a similar sequence were detected in five other 1-haloalkane-degrading Rhodococcus strains. There were no sequences homolo gous to IS2112 found in the l-haloalkane-degrading 'Pseudomonas pavonaceae' 170 and Rhodococcus sp, HA1 or in several Rhodococcus strains which do not utilize haloalkanes, IS2112 was originally found in plasmid pRTL1 of R. rh odochrous NCIMB 13064 which harbours genes encoding utilization of l-haloal kanes, and was located 5 kbp upstream of the haloalkane dehalogenase gene ( dhaA), Although the second copy of IS2112 in strain NCIMB 13064 was also pr esent on the pRTL1 plasmid, these sequences do not apparently comprise a si ngle composite transposon encoding haloalkane utilization. An analysis of d erivatives of NCIMB 13064 revealed that IS2112 was involved in genome rearr angements. IS2112 appeared to change its location as a result of transposit ion and as a result of other rearrangements of the NCIMB 13064 genome.