Tn5, much can also be discovered about other transposases and their activities. Tn5 is utilized in genome sequencing by using the Tn5 to append sequencing adaptors and fragment the DNA in a single enzymatic reaction in 2010, reducing the time and input requirements over traditional next-generation sequencing library preparation. The Tn5-based strategy can simplify the library preparation protocol significantly and can even can be incorporated into the direct colony-PCR for large numbers of bacterial isolates with no obvious coverage bias. The main disadvantages are less control of fragmented size compared to enzymatic fragmentation and mechanical fragmentation, and a bias toward high G-C content. This means of library preparation is also used in the ATAC-seq technique. Sleeping Beauty transposase The Sleeping Beauty (SB) transposase is the recombinase that drives the Sleeping Beauty transposon system. SB transposase belongs to the DD[E/D] family of transposases, which in turn belong to a large superfamily of polynucleotidyl transferases that includes RNase H, RuvC Holliday resolvase, RAG proteins, and retroviral integrases. The SB system is used primarily in vertebrate animals for gene transfer, including gene therapy, and gene discovery. The engineered SB100X is an enzyme that directs the high levels of transposon integration. Tn7 transposon The Tn7 transposon is a mobile genetic element found in many prokaryotes such as Escherichia coli (E. coli), and was first discovered as a DNA sequence in bacterial chromosomes and naturally occurring plasmids that encoded resistance to the antibiotics trimethoprim and streptomycin. Specifically classified as a transposable element (transposon), the sequence can duplicate and move itself within a genome by utilizing a self-encoded recombinase enzyme called a transposase, resulting in effects such as creating or reversing mutations and changing genome size. The Tn7 transposon has developed two mechanisms to promote its propagation among prokaryotes. Like many other bacterial transposons, Tn7 transposes at low-frequency and inserts into many different sites with little to no site-selectivity. Through this first pathway, Tn7 is preferentially directed into conjugable plasmids, which can be replicated and distributed between bacteria. However, Tn7 is unique in that it also transposes at high-frequency into a single specific site in bacterial chromosomes called attTn7. This specific sequence is an essential and highly conserved gene found in many strains of bacteria. However, the recombination is not deleterious to the host bacterium as Tn7 actually transposes downstream of the gene after recognizing it, resulting in a safe way to propagate the transposon without