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Protein–DNA contacts and conformational changes in the Tn 10 transpososome during assembly and activation for cleavage
Author(s) -
Crellin Paul,
Chalmers Ronald
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.14.3882
Subject(s) - biology , tn10 , cleavage (geology) , dna , biophysics , protein structure , plasma protein binding , dna binding protein , microbiology and biotechnology , biochemistry , transposable element , transcription factor , gene , genome , paleontology , fracture (geology)
IHF or supercoiling is required early in Tn 10 transposition, but at later stages they inhibit the reaction in a classic homeostatic loop. We investigated the mechanism of transpososome assembly and regulation using hydroxyl radical DNA protection and interference. We present a three‐dimensional molecular model for the IHF‐bent end of Tn 10 wrapped around a transposase core. Contacts span some 80 bp at the transposon end, but after assembly of an active complex containing metal ion, most contacts become dispensable. These include transposase contacts beyond the IHF site that chaperone assembly of the complex and are needed for efficient cleavage. Single and double‐end breaks do not affect the complex but divalent metal ions promote large conformational changes at bp +1 and the flanking DNA.