... The Lambda C1 repressor consists of two domains connected by a linker: an N-terminal DNA-binding domain that also mediates interactions with RNA polymerase, and a C-terminal dimerisation domain [1]. ... Several different phage repressors from different helix-turn-helix families contain DNA-binding domains that adopt a similar topology. ... Bell C.E. , Frescura P. , Hochschild A. , Lewis M. Crystal structure of the lambda repressor C-terminal domain provides a model for cooperative operator binding. ...