A. Astromoff et M. Ptashne, A VARIANT OF LAMBDA-REPRESSOR WITH AN ALTERED PATTERN OF COOPERATIVE BINDING TO DNA SITES, Proceedings of the National Academy of Sciences of the United Statesof America, 92(18), 1995, pp. 8110-8114
The bacteriophage lambda repressor binds cooperatively to pairs of adj
acent sites in the lambda chromosome, one repressor dimer binding to e
ach site, The repressor's amino domain (that which mediates DNA bindin
g) is connected to its carboxyl domain (that which mediates dimerizati
on and the interaction between dimers) by a protease-sensitive linker
region, We have generated a variant A repressor that lacks this linker
region, We show that dimers of the variant protein are deficient in c
ooperative binding to sites at certain, but not all, distances, The li
nker region thus extends the range over which carboxyl domains of DNA-
bound dimers can interact. In particular, the linker is required for c
ooperative binding to a pair of sites as found in the lambda chromosom
e, and thus is essential for the repressor's physiological function.