TY - JOUR
T1 - Single molecule analysis of Thermus thermophilus SSB protein dynamics on single-stranded DNA
AU - Zhang, Jichuan
AU - Zhou, Ruobo
AU - Inoue, Jin
AU - Mikawa, Tsutomu
AU - Ha, Taekjip
N1 - Funding Information:
National Institutes of Health [RR025341 and GM065367 to T.H.]; National Science Foundation [0822613 and 0646550 to T.H.]; JSPS KAKENHI Grant [22570147]; Howard Hughes Medical Institute (to T.H.). Funding for open access charge: NIH [RR025341 and GM065367 to T.H.]; National Science Foundation [0822613 and 0646550 to T.H.]; JSPS KAKENHI [22570147].
PY - 2014/4
Y1 - 2014/4
N2 - Single-stranded (ss) DNA binding (SSB) proteins play central roles in DNA replication, recombination and repair in all organisms. We previously showed that Escherichia coli (Eco) SSB, a homotetrameric bacterial SSB, undergoes not only rapid ssDNAbinding mode transitions but also one-dimensional diffusion (or migration) while remaining bound to ssDNA. Whereas the majority of bacterial SSB family members function as homotetramers, dimeric SSB proteins were recently discovered in a distinct bacterial lineage of extremophiles, the Thermus-Deinococcus group. Here we show, using single-molecule fluorescence resonance energy transfer (FRET), that homodimeric bacterial SSB from Thermus thermophilus (Tth) is able to diffuse spontaneously along ssDNA over a wide range of salt concentrations (20-500mM NaCl), and that TthSSB diffusion can help transiently melt the DNA hairpin structures. Furthermore, we show that two TthSSB molecules undergo transitions among different DNA-binding modes while remaining bound to ssDNA. Our results extend our previous observations on homotetrameric SSBs to homodimeric SSBs, indicating that the dynamic features may be shared among different types of SSB proteins. These dynamic features of SSBs may facilitate SSB redistribution and removal on/from ssDNA, and help recruit other SSB-interacting proteins onto ssDNA for subsequent DNA processing in DNA replication, recombination and repair.
AB - Single-stranded (ss) DNA binding (SSB) proteins play central roles in DNA replication, recombination and repair in all organisms. We previously showed that Escherichia coli (Eco) SSB, a homotetrameric bacterial SSB, undergoes not only rapid ssDNAbinding mode transitions but also one-dimensional diffusion (or migration) while remaining bound to ssDNA. Whereas the majority of bacterial SSB family members function as homotetramers, dimeric SSB proteins were recently discovered in a distinct bacterial lineage of extremophiles, the Thermus-Deinococcus group. Here we show, using single-molecule fluorescence resonance energy transfer (FRET), that homodimeric bacterial SSB from Thermus thermophilus (Tth) is able to diffuse spontaneously along ssDNA over a wide range of salt concentrations (20-500mM NaCl), and that TthSSB diffusion can help transiently melt the DNA hairpin structures. Furthermore, we show that two TthSSB molecules undergo transitions among different DNA-binding modes while remaining bound to ssDNA. Our results extend our previous observations on homotetrameric SSBs to homodimeric SSBs, indicating that the dynamic features may be shared among different types of SSB proteins. These dynamic features of SSBs may facilitate SSB redistribution and removal on/from ssDNA, and help recruit other SSB-interacting proteins onto ssDNA for subsequent DNA processing in DNA replication, recombination and repair.
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U2 - 10.1093/nar/gkt1316
DO - 10.1093/nar/gkt1316
M3 - Article
C2 - 24371279
AN - SCOPUS:84898935621
SN - 0305-1048
VL - 42
SP - 3821
EP - 3832
JO - Nucleic acids research
JF - Nucleic acids research
IS - 6
ER -