TY - JOUR
T1 - Differential single-stranded DNA binding properties of the paralogous SsbA and SsbB proteins from Streptococcus pneumoniae
AU - Grove, Diane E.
AU - Willcox, Smaranda
AU - Griffith, Jack D.
AU - Bryant, Floyd R.
PY - 2005/3/25
Y1 - 2005/3/25
N2 - The naturally transformable Gram-positive bacterium Streptococcus pneumoniae has two single-stranded DNA-binding (SSB) proteins, designated SsbA and SsbB. The SsbA protein is similar in size to the well characterized SSB protein from Escherichia coli (SsbEc). The SsbB protein, in contrast, is a smaller protein that is specifically induced during natural transformation and has no counterpart in E. coli. In this report, the single-stranded DNA (ssDNA) binding properties of the SsbA and SsbB proteins were examined and compared with those of the SsbEc protein. The ssDNA binding characteristics of the SsbA protein were similar to those of the SsbEc protein in every ssDNA binding assay used in this study. The SsbB protein differed from the SsbA and SsbEc proteins, however, both in its binding to short homopolymeric dTn oligomers (as judged by polyacrylamide gel-shift assays) and in its binding to the longer naturally occurring φX and M13 ssDNAs (as judged by agarose gel-shift assays and electron microscopic analysis). The results indicate that an individual SsbB protein binds to ssDNA with an affinity that is similar or higher than that of the SsbA and SsbEc proteins. However, the manner in which multiple SsbB proteins assemble onto a ssDNA molecule differs from that observed with the SsbA and SsbEc proteins. These results represent the first analysis of paralogous SSB proteins from any bacterial species and provide a foundation for further investigations into the biological roles of these proteins.
AB - The naturally transformable Gram-positive bacterium Streptococcus pneumoniae has two single-stranded DNA-binding (SSB) proteins, designated SsbA and SsbB. The SsbA protein is similar in size to the well characterized SSB protein from Escherichia coli (SsbEc). The SsbB protein, in contrast, is a smaller protein that is specifically induced during natural transformation and has no counterpart in E. coli. In this report, the single-stranded DNA (ssDNA) binding properties of the SsbA and SsbB proteins were examined and compared with those of the SsbEc protein. The ssDNA binding characteristics of the SsbA protein were similar to those of the SsbEc protein in every ssDNA binding assay used in this study. The SsbB protein differed from the SsbA and SsbEc proteins, however, both in its binding to short homopolymeric dTn oligomers (as judged by polyacrylamide gel-shift assays) and in its binding to the longer naturally occurring φX and M13 ssDNAs (as judged by agarose gel-shift assays and electron microscopic analysis). The results indicate that an individual SsbB protein binds to ssDNA with an affinity that is similar or higher than that of the SsbA and SsbEc proteins. However, the manner in which multiple SsbB proteins assemble onto a ssDNA molecule differs from that observed with the SsbA and SsbEc proteins. These results represent the first analysis of paralogous SSB proteins from any bacterial species and provide a foundation for further investigations into the biological roles of these proteins.
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U2 - 10.1074/jbc.M414057200
DO - 10.1074/jbc.M414057200
M3 - Article
C2 - 15647253
AN - SCOPUS:15744364176
SN - 0021-9258
VL - 280
SP - 11067
EP - 11073
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 12
ER -