The Corynebacterium glutamicum insertion sequence ISCg2 prefers conserved target sequences located adjacent to genes involved in aspartate and glutamate metabolism

An IS element, termed ISCg2, was identified in the chromosome of Corynebact erium glutamicum ATCC 13032. After screening a cosmid library of the C. glu tamicum ATCC 13032 genome, six copies of ISCg2 including their flanking reg ions were sequenced and analyzed. ISCg2 is 1636 bp in length and has 26-bp imperfect inverted repeats flanked by 3-bp direct repeats. By comparisons w ith other IS elements,ISCg2 was classified as a member of the IS30 family o f insertion sequences. The six copies of ISCg2 were identical at the nucleo tide level and were located in intergenic, AT-rich regions of the chromosom e. The regions in which the six copies of ISCg2 were inserted displayed sig nificant similarities. This similarity extends over a region of 65 bp, whic h was assumed to be the target region for ISCg2. Interestingly, live of the six copies of ISCg2 were located adjacent to genes that may be involved in aspartate and glutamate metabolism or its regulation. Investigation of the distribution of ISCg2 showed that the IS element is restricted to certain C. glutamicum strains. Analysis of various integration regions indicates ac tive transposition of ISCg2. in C. glutamicum.