Corynebacterium striatum chloramphenicol resistance transposon Tn5564: genetic organization and transposition in...

The clinical isolate Corynebacterium striatum M82B (formerly Corynebacterium xerosis M82B) carries the 50-kb R-plasmid pTP10 conferring resistance to the antibiotics chloramphenicol, erythromycin, kanamycin, and tetracycline. DNA sequence analysis of the chloramphenicol resistance region revealed the presence of the 4155-bp transposable element Tn5564. The ends of Tn5564 are identical 22-bp inverted repeats flanked by a 6-bp target site duplication. The central region of Tn5564 encodes the chloramphenicol resistance gene cmx, specifying a transmembrane chloramphenicol efflux protein, and an open reading frame homologous to transposases of insertion sequences identified in Arthrobacter nicotinovorans and Bordetella pertussis. Furthermore, the 1715-bp insertion sequence IS1513 encoding a putative transposase of the IS30 family is an integral part of Tn5564 and is located upstream of cmx. For transposon mutagenesis, Tn5564 was transferred to Corynebacterium glutamicum on a mobilizable Escherichia coli plasmid using RP4-mediated intergeneric conjugation. Transposition of Tn5564 in C. glutamicum occurred with a frequency of 3.3 x 10(-8) and resulted in an insertion into target sites containing the central palindromic tetranucleotide CTAG. A Tn5564-induced mutant strain of C. glutamicum was found to carry the transposon in the ftsZ gene region.