2pij
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(New page: 200px<br /><applet load="2pij" size="350" color="white" frame="true" align="right" spinBox="true" caption="2pij, resolution 1.700Å" /> '''Structure of the Cr...)
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Revision as of 11:21, 5 March 2008
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Structure of the Cro protein from prophage Pfl 6 in Pseudomonas fluorescens Pf-5
Overview
Proteins that share common ancestry may differ in structure and function because of divergent evolution of their amino acid sequences. For a typical diverse protein superfamily, the properties of a few scattered members are known from experiment. A satisfying picture of functional and structural evolution in relation to sequence changes, however, may require characterization of a larger, well chosen subset. Here, we employ a "stepping-stone" method, based on transitive homology, to target sequences intermediate between two related proteins with known divergent properties. We apply the approach to the question of how new protein folds can evolve from preexisting folds and, in particular, to an evolutionary change in secondary structure and oligomeric state in the Cro family of bacteriophage transcription factors, initially identified by sequence-structure comparison of distant homologs from phages P22 and lambda. We report crystal structures of two Cro proteins, Xfaso 1 and Pfl 6, with sequences intermediate between those of P22 and lambda. The domains show 40% sequence identity but differ by switching of alpha-helix to beta-sheet in a C-terminal region spanning approximately 25 residues. Sedimentation analysis also suggests a correlation between helix-to-sheet conversion and strengthened dimerization.
About this Structure
2PIJ is a Protein complex structure of sequences from Pseudomonas fluorescens with , and as ligands. Known structural/functional Sites: , , , , and . Full crystallographic information is available from OCA.
Reference
Transitive homology-guided structural studies lead to discovery of Cro proteins with 40% sequence identity but different folds., Roessler CG, Hall BM, Anderson WJ, Ingram WM, Roberts SA, Montfort WR, Cordes MH, Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2343-8. Epub 2008 Jan 28. PMID:18227506
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