2ovg
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Lambda Cro Q27P/A29S/K32Q triple mutant at 1.35 A in space group P3221
OverviewOverview
Previously reported crystal structures of free and DNA-bound dimers of, lambda Cro differ strongly (about 4 A backbone rmsd), suggesting both, flexibility of the dimer interface and induced-fit protein structure, changes caused by sequence-specific DNA binding. Here, we present two, crystal structures, in space groups P3(2)21 and C2 at 1.35 and 1.40 A, resolution, respectively, of a variant of lambda Cro with three mutations, in its recognition helix (Q27P/A29S/K32Q, or PSQ for short). One dimer, structure (P3(2)21; PSQ form 1) resembles the DNA-bound wild-type Cro, dimer (1.0 A backbone rmsd), while the other (C2; PSQ form 2) resembles, neither unbound (3.6 A) nor bound (2.4 A) wild-type Cro. Both PSQ form 2, and unbound wild-type dimer crystals have a similar interdimer beta-sheet, interaction between the beta1 strands at the edges of the dimer. In the, former, an infinite, open beta-structure along one crystal axis results, while in the latter, a closed tetrameric barrel is formed. Neither the, DNA-bound wild-type structure nor PSQ form 1 contains these interdimer, interactions. We propose that beta-sheet superstructures resulting from, crystal contact interactions distort Cro dimers from their preferred, solution conformation, which actually resembles the DNA-bound structure., These results highlight the remarkable flexibility of lambda Cro but also, suggest that sequence-specific DNA binding may not induce large changes in, the protein structure.
About this StructureAbout this Structure
2OVG is a Single protein structure of sequence from Enterobacteria phage lambda with and as ligands. Known structural/functional Sites: and . Full crystallographic information is available from OCA.
ReferenceReference
Two structures of a lambda Cro variant highlight dimer flexibility but disfavor major dimer distortions upon specific binding of cognate DNA., Hall BM, Roberts SA, Heroux A, Cordes MH, J Mol Biol. 2008 Jan 18;375(3):802-11. Epub 2007 Nov 6. PMID:18054042
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