A novel family of potentially mobile DNA elements encoding site-specific gene-integration functions: integrons.

摘要: A family of novel mobile DNA elements is described, examples which are found at several independent locations and encode a variety antibiotic resistance genes. The complete consist two conserved segments separated by segment variable length sequence includes inserted located 3' to the genes was sequenced from Tn21 R46, sequences identical over region 2026 bases, sulphonamide gene sull, further open reading frames unknown function. both 5' regions element have been determined. 59-base element, junctions segment, also present this location in R46 sequence. copy one half end sull gene, suggesting that though part region, originally into an ancestral site-specific integration. Inverted or direct terminal repeats short target site duplications, characteristics class I II transposons, not outer boundaries described here. Furthermore, do any proteins related known transposition proteins, except integrase encoded implicated insertion process. Mobilization has observed experimentally; mobility implied identification least four locations, Tn21, (IncN), R388 (IncW) Tn1696. definitive features these (i) they include integration functions (the site); (ii) able acquire various units act as expression cassette supplying promoter for As consequence acquiring different genes, exists forms differ number nature This appears formally distinct other we propose name elements, integrons.