The Transposon Registry

This integrative and conjugative element (ICE) was found upstream of the cfiA carbapenemase gene in Bacteroides fragilis strain Tbg-22. The 3' end of Tn7563 possesses sequences matching the Bacteroides promoter structure, and we found evidence that Tn7563 contributes to upregulation of cfiA expression in Tbg-22. We demonstrated in vitro circularisation of Tn7563 in strain Tbg-22 using PCR. Several Bacteroides spp. genomes in GenBank contain ICEs highly similar to Tn7563. Some of them are about twice the size of Tn7563, with one half highly similar to Tn7563. In all cases, these ICEs in other published genomes were found to be inserted at the 3' end of a tRNA-Ser gene.