A unique right end-enhancer complex precedes synapsis of Mu ends: the enhancer is sequestered within the transpososome throughout transposition.
Assembly of the Mu transpososome is dependent on interactions of transposase subunits with the left (L) and right (R) ends of Mu and an enhancer (E). We have followed the order and dynamics of association of these sites within a series of transpososomes prior to and during formation of a three-site complex (LER), engagement of Mu ends by the transposase active site (type 0 complex), cleavage of the ends (type I complex) and their transfer to target DNA (type II complex). LER appears to be preceded by a two-site complex (ER) where E and R are interwrapped twice, as in the mature transpososome. At each stage thereafter, the overall topology of five DNA supercoils is retained: two between E and R, one between E and L and two between L and R. However, L-R interactions within LER appear to be flexible. Unexpectedly, the enhancer was seen to persist within the transpososome through cleavage and strand transfer of Mu ends to target DNA.
Pathania
Shailja
S
Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Jayaram
Makkuni
M
Harshey
Rasika M
RM
D001287:Attachment Sites, Microbiological / Q000235:genetics; D010583:Bacteriophage mu / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D023902:Chromosome Pairing / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D019426:Integrases; D008954:Models, Biological; D011995:Recombination, Genetic; D019895:Transposases / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins
D004251:DNA Transposable Elements; D004278:DNA, Superhelical; D014764:Viral Proteins; C045073:Cre recombinase; D019426:Integrases; D019895:Transposases