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T-rich DNA single strands bind to a preformed site on the bacterial cold shock protein Bs-CspB

Item Type:Article
Title:T-rich DNA single strands bind to a preformed site on the bacterial cold shock protein Bs-CspB
Creators Name:Max, K.E.A., Zeeb, M., Bienert, R., Balbach, J. and Heinemann, U.
Abstract:Bacterial cold shock proteins (CSPs) are involved in cellular adaptation to cold stress. They bind to single-stranded nucleic acids with a K(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(6)) at a resolution of 1.78 A. Bs-CspB binds to dT(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.
Keywords:Cold Shock Proteins, Cold Shock Response, DNA Binding Proteins, RNA Chaperone Activity, Transcription Antitermination
Source:Journal of Molecular Biology
Page Range:702-714
Date:14 July 2006
Official Publication:https://doi.org/10.1016/j.jmb.2006.05.044
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