TY - JOUR
T1 - SSB protein diffusion on single-stranded DNA stimulates RecA filament formation
AU - Roy, Rahul
AU - Kozlov, Alexander G.
AU - Lohman, Timothy M.
AU - Ha, Taekjip
N1 - Funding Information:
Acknowledgements We thank C. Joo, S. A. McKinney, I. Rasnik, S. Hohng and S. Myong for experimental help and discussion; C. Murphy, M. Nahas and K. Raghunathan for discussion; T. Ho and A. Niedziela-Majka for help with DNA and protein preparation, respectively; and R. Porter for the SSB expression plasmid. T.H. is an employee of the Howard Hughes Medical Institute. These studies were supported by grants from the National Institutes of Health and the National Science Foundation.
PY - 2009/10/22
Y1 - 2009/10/22
N2 - Single-stranded DNA generated in the cell during DNA metabolism is stabilized and protected by binding of ssDNA-binding (SSB) proteins. Escherichia coli SSB, a representative homotetrameric SSB, binds to ssDNA by wrapping the DNA using its four subunits. However, such a tightly wrapped, high-affinity protein-DNA complex still needs to be removed or repositioned quickly for unhindered action of other proteins. Here we show, using single-molecule two- and three-colour fluorescence resonance energy transfer, that tetrameric SSB can spontaneously migrate along ssDNA. Diffusional migration of SSB helps in the local displacement of SSB by an elongating RecA filament. SSB diffusion also melts short DNA hairpins transiently and stimulates RecA filament elongation on DNA with secondary structure. This observation of diffusional movement of a protein on ssDNA introduces a new model for how an SSB protein can be redistributed, while remaining tightly bound to ssDNA during recombination and repair processes.
AB - Single-stranded DNA generated in the cell during DNA metabolism is stabilized and protected by binding of ssDNA-binding (SSB) proteins. Escherichia coli SSB, a representative homotetrameric SSB, binds to ssDNA by wrapping the DNA using its four subunits. However, such a tightly wrapped, high-affinity protein-DNA complex still needs to be removed or repositioned quickly for unhindered action of other proteins. Here we show, using single-molecule two- and three-colour fluorescence resonance energy transfer, that tetrameric SSB can spontaneously migrate along ssDNA. Diffusional migration of SSB helps in the local displacement of SSB by an elongating RecA filament. SSB diffusion also melts short DNA hairpins transiently and stimulates RecA filament elongation on DNA with secondary structure. This observation of diffusional movement of a protein on ssDNA introduces a new model for how an SSB protein can be redistributed, while remaining tightly bound to ssDNA during recombination and repair processes.
UR - https://www.scopus.com/pages/publications/70350488396
U2 - 10.1038/nature08442
DO - 10.1038/nature08442
M3 - Article
C2 - 19820696
AN - SCOPUS:70350488396
SN - 0028-0836
VL - 461
SP - 1092
EP - 1097
JO - Nature
JF - Nature
IS - 7267
ER -