부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jmb.2006.05.044 Byline: Klaas E.A. Max (1), Markus Zeeb (2)(5), Ralf Bienert (1), Jochen Balbach (2)(3), Udo Heinemann (1)(4) Keywords: cold shock proteins; cold shock response; DNA binding proteins; RNA chaperone activity; transcription antitermination Abbreviations: CSP, cold shock protein; RNP, ribonucleoprotein; OB, oligonucleotide/oligosaccharide binding; Ec, Escherichia coli; Bs, Bacillus subtilis; Bc, Bacillus caldolyticus; Tm, Thermotoga maritima; ss, single-stranded; PDB, Protein Data Bank Abstract: Bacterial cold shock proteins (CSPs) are involved in cellular adaptation to cold stress. They bind to single-stranded nucleic acids with a K.sub.D value in the micro- to nanomolar range. Here we present the structure of the Bacillus subtilis CspB (Bs-CspB) in complex with hexathymidine (dT.sub.6) at a resolution of 1.78 A. Bs-CspB binds to dT.sub.6 with nanomolar affinity via an amphipathic interface on the protein surface. Individual binding subsites interact with single nucleobases through stacking interactions and hydrogen bonding. The sugar-phosphate backbone and the methyl groups of the thymine nucleobases remain solvent exposed and are not contacted by protein groups. Fluorescence titration experiments monitoring the binding of oligopyrimidines to Bs-CspB reveal binding preferences at individual subsites and allow the design of an optimised heptapyrimidine ligand, which is bound with sub-nanomolar affinity. This study reveals the stoichiometry and sequence determinants of the binding of single-stranded nucleic acids to a preformed site on Bs-CspB and thus provides the structural basis of the RNA chaperone and transcription antitermination activities of the CSP. Author Affiliation: (1) Max-Delbruck-Centrum fur Molekulare Medizin 13125 Berlin, Germany (2) Lehrstuhl fur Biochemie, Universitat Bayreuth, 95440 Bayreuth, Germany (3) Fachgruppe Biophysik, Fachbereich Physik, Martin-Luther-Universitat Halle-Wittenberg, 06120 Halle (Saale), Germany (4) Institut fur Chemie und Biochemie, Freie Universitat 14195 Berlin, Germany (5) Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92073, USA Article History: Received 10 March 2006; Revised 10 May 2006; Accepted 17 May 2006 Article Note: (miscellaneous) Edited by K. Morikawa