Structural aspects of a higher order nucleoprotein complex: induction of an altered DNA structure at the Mu‐host junction of the Mu type 1 transpososome.

摘要: The Mu in vitro strand transfer reaction proceeds via two stable higher order nucleoprotein complexes, the Type 1 and 2 transpososomes. A protein is responsible for structural functional integrity of transpososome. We have investigated quaternary structure within this complex by chemical cross-linking experiments found that basic unit an tetramer. Three binding sites transpososome are protected DNase I footprinting: outermost L1 R1, as well R2. Genetic evidence also presented which corroborates result. Efficient formation complexes occurs mini-Mus with L3 or R3 deleted when L2 site has been substituted; but no absence protection at R1 extends 12-13 bp beyond Mu-host junctions seen methidiumpropyl-EDTA.Fe(II) [MPE.Fe(II)] foot-printing, indicating contacts flanking host sequences not on linear DNA; furthermore, hydroxyl radical footprinting shows unprecedentedly large enhancement continuous strand, nick outside right end, suggests altered DNA induced upon formation.