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The integration‐excision system of the conjugative transposon Tn 1545 is structurally and functionally related to those of lambdoid phages
Author(s) -
PoyartSalmeron C.,
TrieuCuot P.,
Carlier C.,
Courvalin P.
Publication year - 1990
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1990.tb02062.x
Subject(s) - transposable element , biology , complementation , genetics , dna transposable elements , homology (biology) , integrases , insertion sequence , plasmid , genome , gene , phenotype
Summary Excision of Tn1545 and related conjugative transposons of Gram‐positive bacteria occurs by reciprocal site‐specific recombination between non‐homologous regions of the transposon‐target junctions. Excisive recombination requires two transposon‐encoded proteins designated Xis‐Tn and Int‐Tn. We have shown that, following excision, Tn1545 is a circular structure with ends separated by either of the two hexanucleotides that were present at the transposon‐target junctions. Using a trans ‐complementation assay, we have demonstrated that Int‐Tn is able to catalyse in vivo integration of a circular intermediate of Tn1545 defective for integration and excision. Comparison of integration sites suggests that limited sequence homology at the vicinity of the recombining sites is required for integration of the element. These data support the hypothesis that the integration/excision systems of conjugative transposons from Grampositive cocci and of lambdoid phages from Gramnegative bacilli have evolved from a common ancestor.