Abstract
Tn916, the most typical conjugative transposon carrying the tetM resistance gene, has been identified in a wide range of genomes. This study utilized the sequence identity of the Tn916 internal integrase in Enterococcus faecalis DS16 to recognize Tn916 (with an identity of > 90%) and Tn916 family members (with identity between 60%-90%) in all currently complete genomes and chromosomes, naming them Tn916.1- Tn916.9, respectively. Tn916 and its family members have similar structures: AT-rich inverted repeats (IRs), with boundaries being AT-rich stem-loop structures; the coupling sequences in the middle are often 5 bp AT-rich regions, and their conserved base being the first base A or the last base T; the stem sequence from the host often matches or complement part of the IR (4 or 5bp). Most Tn916 family members have the ABC gene cluster as their resistance marker gene, and Tn916.7 has vancomycin resistance. Tn916 and its family integrate into genomes which have lower GC% more frequently. Our research revealed the flanking structure characteristics of Tn916 and its family, laying a molecular foundation for further determining their deletion and integration mechanisms, and aiding in controlling the spread of such antibiotic resistance in these conjugative transposons.