Characterization of IS1676 from Rhodococcus erythropolis SQ1

To develop a transposable element-based system for mutagenesis in Rhodococc us, we used the sacB gene from Bacillus subtilis to isolate a novel transpo sable element, IS1676, from R, erythropolis SQ1. This 1693 bp insertion seq uence is bounded by imperfect (10 out of 13 bp) inverted repeats and it cre ates 4 bp direct repeats upon insertion. Comparison of multiple insertion s ites reveals a preference for the sequence 5'-(C/T)TA(A/G)-3' in the target site. IS1676 contains a single, large (1446 bp) open reading frame with co ding potential for a protein of 482 amino acids. IS1676 may be similar to a n ancestral transposable element that gave rise to repetitive sequences ide ntified in clinical isolates of Mycobacterium kansasii. Derivatives of IS16 76 should be useful for analysis of Rhodococcus strains. for which few othe r genetic tools are currently available.