T-rich DNA single strands bind to a preformed site on the bacterial cold shock protein Bs-CspB.
J Mol Biol
; 360(3): 702-14, 2006 Jul 14.
Article
em En
| MEDLINE
| ID: mdl-16780871
ABSTRACT
Bacterial cold shock proteins (CSPs) are involved in cellular adaptation to cold stress. They bind to single-stranded nucleic acids with a KD value in the micro- to nanomolar range. Here we present the structure of the Bacillus subtilis CspB (Bs-CspB) in complex with hexathymidine (dT6) at a resolution of 1.78 A. Bs-CspB binds to dT6 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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Timina
/
Bacillus subtilis
/
Proteínas de Bactérias
/
DNA de Cadeia Simples
/
Proteínas de Choque Térmico
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Alemanha