Role of cis-acting sites in stimulation of the phage λ P(RM) promoter by CI-mediated looping.

ABSTRACT: The lysogenic state of phage λ is maintained by the CI repressor. CI binds to three operators each in the right operator (O(R)) and left operator (O(L)) regions, which lie 2.4 kb apart. At moderate CI levels, the predominant binding pattern is two dimers of CI bound cooperatively at each regulatory region. The resulting tetramers can then interact, forming an octamer and a loop of the intervening DNA. CI is expressed from the P(RM) promoter, which lies in the O(R) region and is subjected to multiple regulatory controls. Of these, the most recently discovered is stimulation by loop formation. In this work, we have investigated the mechanism by which looping stimulates P(RM). We find that two cis-acting sites lying in the O(L) region are involved. One site, an UP element, is required for sti

SUBMITTER: Michalowski CB 

PROVIDER: S-EPMC3719544 | biostudies-literature | 2013 Aug

REPOSITORIES: biostudies-literature