title: Transposon Tn10: genetic organization, regulation, and insertion specificity.
abstract: Transposon Tn10 is a composite element in which two individual insertion sequence (IS)-like sequences cooperate to mediate transposition of the intervening material. The two flanking IS10 elements are not identical; IS10-right is responsible for functions required to promote transposition, and IS10-left is defective in transposition functions. We suggest that the two IS10 elements were originally identical in sequence and have subsequently diverged. IS10-right is compactly organized with structural gene(s), promoters, and sites important for transposition and (presumably) its regulation all closely linked and, in some cases, overlapping. IS10 has a single major coding region that almost certainly encodes an essential transposition function. A pair of opposing promoters flank the start of this coding region. One of these promoters is responsible for expression in vivo of transposon-encoded transposition functions. We propose that the second promoter is involved in modulation of Tn10 transposition. Genetic analysis suggests that transposon-encoded function(s) may be preferentially cis-acting. Insertion of Tn10 into particular preferred target sites is due primarily to the occurrence of a particular six-base pair target DNA sequence. The properties of this sequence suggest that symmetrically disposed subunits of a single protein may be responsible for both recognition and cleavage of target DNA during insertion.
mesh_terms: D001483:Base Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D009876:Operon; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D012475:Salmonella / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial