2i5m
Crystal structure of Bacillus subtilis cold shock protein CspB variant A46K S48R
Structural highlights
FunctionCSPB_BACSU Binds to the pentamer sequences ATTGG and CCAAT with highest affinity in single-stranded DNA, and also to other sequences. Has greater affinity for ATTGG than CCAAT. Can act as transcriptional activator of cold shock genes by recognizing putative ATTGG-box elements present in promoter regions of genes induced under cold shock conditions. 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 bacterial cold shock proteins (Csp) are widely used as models for the experimental and computational analysis of protein stability. In a previous study, in vitro evolution was employed to identify strongly stabilizing mutations in Bs-CspB from Bacillus subtilis. The best variant found by this approach contained the mutations M1R, E3K and K65I, which raised the midpoint of thermal unfolding of Bs-CspB from 53.8 degrees C to 83.7 degrees C, and increased the Gibbs free energy of stabilization by 20.9 kJ mol(-1). Another selected variant with the two mutations A46K and S48R was stabilized by 11.1 kJ mol(-1). To elucidate the molecular basis of these stabilizations, we determined the crystal structures of these two Bs-CspB variants. The mutated residues are generally well ordered and provide additional stabilizing interactions, such as charge interactions, additional hydrogen bonds and improved side-chain packing. Several mutations improve the electrostatic interactions, either by the removal of unfavorable charges (E3K) or by compensating their destabilizing interactions (A46K, S48R). The stabilizing mutations are clustered at a contiguous surface area of Bs-CspB, which apparently is critically important for the stability of the beta-barrel structure but not well optimized in the wild-type protein. Optimized variants of the cold shock protein from in vitro selection: structural basis of their high thermostability.,Max KE, Wunderlich M, Roske Y, Schmid FX, Heinemann U J Mol Biol. 2007 Jun 15;369(4):1087-97. Epub 2007 Apr 12. PMID:17481655[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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