TY - JOUR
T1 - Stimulation of the Streptococcus pneumoniae RecA protein-promoted three-strand exchange reaction by the competence-specific SsbB protein
AU - Grove, Diane E.
AU - Anne, Geetha
AU - Hedayati, Mohammad A.
AU - Bryant, Floyd R.
PY - 2012/7/20
Y1 - 2012/7/20
N2 - 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.
AB - 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.
KW - DNA strand exchange
KW - Natural transformation
KW - RecA protein
KW - SSB protein
KW - Streptococcus pneumoniae
UR - http://www.scopus.com/inward/record.url?scp=84864112639&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84864112639&partnerID=8YFLogxK
U2 - 10.1016/j.bbrc.2012.06.059
DO - 10.1016/j.bbrc.2012.06.059
M3 - Article
C2 - 22713474
AN - SCOPUS:84864112639
SN - 0006-291X
VL - 424
SP - 40
EP - 44
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -