2r63 | pdb_00002r63
STRUCTURAL ROLE OF A BURIED SALT BRIDGE IN THE 434 REPRESSOR DNA-BINDING DOMAIN, NMR, 20 STRUCTURES
Structural highlights
FunctionRPC1_BP434 Binds to two sets of three contiguous operator sites in the phage genome. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe independently folding 63-residue N-terminal DNA-binding domain of the 434 repressor, 434(1-63), contains a buried Arg10-Glu35 salt bridge. A corresponding salt bridge is found in a variety of prokaryotic and eukaryotic DNA-binding proteins with helix-turn-helix motifs. Here, the NMR solution structures of 434(1-63) and the mutant protein 434[R10M](1-63) were determined to investigate the structural role of this salt bridge. Both proteins contain the same type of global fold, with five alpha-helices and a helix-turn-helix motif formed by the helices II and III. The primary structural difference caused by the Arg10 --> Met mutation is a translation of helix I along its axis relative to the helix II-turn-helix III motif. This limited conformational change is paralleled by a 9 kJ M(-1) decrease of the stability of the folded mutant protein in aqueous solution at pH 4.8. It affects the pKa value of Glu19 as well as the population of a hydrogen bond between the backbone amide proton of Asn16 and the side-chain carboxylate group of Glu19. Using the crystal structure of the 434 repressor dimer complexed with the operator DNA as a basis, model building of the DNA complex with the NMR structure of 434[R10M](1-63) shows that Asn16, which is located on the protein surface, makes direct contact with the DNA and indicates that the point mutation Arg10 --> Met should also lead to modifications of the protein-protein contacts in the complex. Structural role of a buried salt bridge in the 434 repressor DNA-binding domain.,Pervushin K, Billeter M, Siegal G, Wuthrich K J Mol Biol. 1996 Dec 20;264(5):1002-12. PMID:9000626[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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