Excision and insertion of the conjugative transposon Tn916 involves a novel recombination mechanism.
The covalently closed circular form of the conjugative transposon Tn916, which acts as an intermediate in transposition, is produced by a novel type of recombination. Excision of the element pairs noncomplementary base pairs, which flank the transposon in a heteroduplex, at the joint of a circular form. By a reversal of the excision process, the base pairs from the heteroduplex are inserted into the next target. We present a detailed molecular model for the movement of conjugative transposons that involves the initial formation of staggered nicks in the "coupling regions" that flank the inserted element. The different products of excision and insertion of Tn916 can be explained by this model.
Caparon
M G
MG
Department of Microbiology and Immunology, Emory University Health Science Center, Atlanta, Georgia 30322.
Scott
J R
JR
D001482:Base Composition; D001483:Base Sequence; D015139:Blotting, Southern; D002678:Chimera; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D004270:DNA, Circular / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D011995:Recombination, Genetic
D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004270:DNA, Circular; D009692:Nucleic Acid Heteroduplexes