Mobile elements carrying ermF and tetQ genes in Gram-positive and Gram-negative bacteria

Bacteroides spp. conjugative transposon Tn5030 is 150 kb which includes a 4 3 kb characterized region containing a number of defined genes and an open reading frame (ORF). The 43 kb region is organized with the ORF1 immediatel y upstream from the ermF gene, coding for an rRNA methylase, then an unknow n 20 kb region downstream followed by the tetQ gene (coding for a ribosomal protection protein) then the rteA and rteB genes. The role of ORF1 is uncl ear; rteA is a putative sensor and rteB a regulator. Thirty-seven (62%) of 60 isolates, representing one Gram-positive anaerobic and 13 Gram-negative anaerobic species, co-transferred the ermF and tetQ genes to an unrelated E nterococcus faecalis recipient. We used the polymerase chain reaction to sh ow the linkage between ORF1, ermF, tetQ, rteA and rteB. Our data suggest th at the ORF1 gene product may participate in the transfer of the ermF gene w ith or without the ORF1-rteB region and has homology to bacterial transposa ses. Isolates that co-transferred the ermF and tetQ genes carried and trans ferred the rteB gene, suggesting that the rteB gene product may be importan t in transfer of the 43 kb ORF1-rteB region to E. faecalis. The rfeB gene p roduct is not required when ermF is transferred independently of tetQ.