Novel DNA binding domain and genetic regulation model of Bacillus subtilis transition state regulator abrB.

We have determined the high resolution NMR solution structure of the novel DNA binding domain of the Bacillus subtilis transition state regulator AbrB. Comparisons of the AbrB DNA binding domain with DNA binding proteins of known structure show that it is a member of a completely novel class of DNA recognition folds that employs a dimeric topology for cellular function. This new DNA binding conformation is referred to as the looped-hinge helix fold. Sequence homology investigations show that this DNA binding topology is found in other disparately related microbes. Structural analysis of the AbrB DNA binding domain together with bioanalytical and mutagenic data of full length AbrB allows us to construct a general model that describes the genetic regulation properties of AbrB.