IS200: an old and still bacterial transposon.
IS200 is a mobile element found in a variety of eubacterial genera, such as Salmonella, Escherichia, Shigella, Vibrio, Enterococcus, Clostridium, Helicobacter, and Actinobacillus. In addition, IS200-like elements are found in archaea. IS200 elements are very small (707-711 bp) and contain a single gene. Cladograms constructed with IS200 DNA sequences suggest that IS200 has not spread among eubacteria by horizontal transfer; thus it may be an ancestral component of the bacterial genome. Self-restraint may have favored this evolutionary endurance; in fact, unlike typical mobile elements, IS200 transposes rarely. Tight repression of transposase synthesis is achieved by a combination of mechanisms: inefficient transcription, protection from impinging transcription by a transcriptional terminator, and repression of translation by a stem-loop mRNA structure. A consequence of IS200 self-restraint is that the number and distribution of IS200 elements remain fairly constant in natural populations of bacteria. This stability makes IS200 a suitable molecular marker for epidemiological and ecological studies, especially when the number of IS200 copies is high. In Salmonella enterica, IS200 fingerprinting is extensively used for strain discrimination.
Beuzón
Carmen R
CR
Department of Genetics, School of Biology, University of Sevilla, Sevilla, 41012 Sevilla, Spain.
Chessa
Daniela
D
Casadesús
Josep
J
D001105:Archaea / Q000235:genetics; D001419:Bacteria / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics
D004251:DNA Transposable Elements; D004269:DNA, Bacterial