Fis targets assembly of the Xis nucleoprotein filament to promote excisive recombination by phage lambda.

ABSTRACT: The phage-encoded Xis protein is the major determinant controlling the direction of recombination in phage lambda. Xis is a winged-helix DNA binding protein that cooperatively binds to the attR recombination site to generate a curved microfilament, which promotes assembly of the excisive intasome but inhibits formation of an integrative intasome. We find that lambda synthesizes surprisingly high levels of Xis immediately upon prophage induction when excision rates are maximal. However, because of its low sequence-specific binding activity, exemplified by a 1.9 A co-crystal structure of a non-specifically bound DNA complex, Xis is relatively ineffective at promoting excision in vivo in the absence of the host Fis protein. Fis binds to a segment in attR that almost entirely overlaps one of t

SUBMITTER: Papagiannis CV 

PROVIDER: S-EPMC1852488 | biostudies-literature | 2007 Mar

REPOSITORIES: biostudies-literature