TY - JOUR TI - Structural dynamics of E. coli single-stranded DNA binding protein reveal DNA wrapping and unwrapping pathways AU - Suksombat, Sukrit AU - Khafizov, Rustem AU - Kozlov, Alexander G AU - Lohman, Timothy M AU - Chemla, Yann R A2 - Kuriyan, John VL - 4 PY - 2015 DA - 2015/08/25 SP - e08193 C1 - eLife 2015;4:e08193 DO - 10.7554/eLife.08193 UR - https://doi.org/10.7554/eLife.08193 AB - Escherichia coli single-stranded (ss)DNA binding (SSB) protein mediates genome maintenance processes by regulating access to ssDNA. This homotetrameric protein wraps ssDNA in multiple distinct binding modes that may be used selectively in different DNA processes, and whose detailed wrapping topologies remain speculative. Here, we used single-molecule force and fluorescence spectroscopy to investigate E. coli SSB binding to ssDNA. Stretching a single ssDNA-SSB complex reveals discrete states that correlate with known binding modes, the likely ssDNA conformations and diffusion dynamics in each, and the kinetic pathways by which the protein wraps ssDNA and is dissociated. The data allow us to construct an energy landscape for the ssDNA-SSB complex, revealing that unwrapping energy costs increase the more ssDNA is unraveled. Our findings provide insights into the mechanism by which proteins gain access to ssDNA bound by SSB, as demonstrated by experiments in which SSB is displaced by the E. coli recombinase RecA. KW - single stranded DNA binding protein KW - optical tweezer KW - energy landscape KW - protein-nucleic acid interaction KW - single molecule JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -