Pinkett, H.Shearwin, K.Stayrook, S.Dodd, I.Burr, T.Hochschild, A.Egan, J.Lewis, M.2007-01-172007-01-172006Molecular Cell, 2006; 21(5):605-6151097-41641097-2765http://hdl.handle.net/2440/23998Bacteriophage λ is a paradigm for understanding the role of cooperativity in gene regulation. Comparison of the regulatory regions of λ and the unrelated temperate bacteriophage 186 provides insight into alternate ways to assemble functional genetic switches. The structure of the C-terminal domain of the 186 repressor, determined at 2.7 Å resolution, reveals an unusual heptamer of dimers, consistent with presented genetic studies. In addition, the structure of a cooperativity mutant of the full-length 186 repressor, identified by genetic screens, was solved to 1.95 Å resolution. These structures provide a molecular basis for understanding lysogenic regulation in 186. Whereas the overall fold of the 186 and λ repressor monomers is remarkably similar, the way the two repressors cooperatively assemble is quite different and explains in part the differences in their regulatory activity.enCopyright © 2007 ElsevierBacteriophage lambdaColiphagesRepressor ProteinsViral ProteinsDNA, ViralCrystallography, X-RayAmino Acid SubstitutionVirus AssemblyGene Expression Regulation, ViralProtein Structure, TertiaryStructure-Activity RelationshipDimerizationJournal article002006034310.1016/j.molcel.2006.01.0190002361350000032-s2.0-3334446163253049Shearwin, K. [0000-0002-7736-2742]Dodd, I. [0000-0003-2969-6841]