Stimulation of the Streptococcus pneumoniae RecA protein-promoted three-strand exchange reaction by the competence-specific SsbB protein

Diane E. Grove, Geetha Anne, Mohammad A. Hedayati, Floyd R. Bryant

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of the transformational competence-specific Streptococcus pneumoniae single-stranded DNA binding protein, SpSsbB, on the ATP-dependent three-strand exchange activity of the SpRecA protein was investigated. Although SpRecA exhibited only a trace level of strand exchange activity in the absence of SpSsbB, an extensive strand exchange reaction was observed when SpSsbB was added to the reaction solution after SpRecA. A more limited strand exchange reaction was observed, however, when SpSsbB was added to the reaction solution before SpRecA. This dependence on the order of addition, together with additional DNA-dependent ATP hydrolysis experiments, indicated that the mechanism of stimulation may involve the postsynaptic binding of SpSsbB to the displaced linear single-stranded DNA reaction product. When dATP was provided in place of ATP as the nucleotide cofactor (to suppress a potentially inhibitory effect of SpSsbB on the interaction of SpRecA with the circular ssDNA reaction substrate), the stimulatory effect of SpSsbB on the strand exchange reaction was apparent regardless of the order in which it was added to the reaction solution. These findings suggest that SpSsbB may be able to facilitate SpRecA-promoted DNA recombination reactions during natural transformation in S. pneumoniae.

Original languageEnglish (US)
Pages (from-to)40-44
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume424
Issue number1
DOIs
StatePublished - Jul 20 2012

Keywords

  • DNA strand exchange
  • Natural transformation
  • RecA protein
  • SSB protein
  • Streptococcus pneumoniae

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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