SSB binds to the RecG and PriA helicases in vivo in the absence of DNA |
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| Authors: | Cong Yu Hui Yin Tan Meerim Choi Adam J. Stanenas Alicia K. Byrd Kevin D. Raney Christopher S. Cohan Piero R. Bianco |
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| Affiliation: | 1. Department of Biochemistry, University at Buffalo, Buffalo, NY, USA;2. Department of Microbiology and Immunology, University at Buffalo, Buffalo, NY, USA;3. Center for Single Molecule Biophysics, University at Buffalo, Buffalo, NY, USA;4. Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, USA;5. Department of Pathology and Anatomical Sciences, University at Buffalo, Buffalo, NY, USA |
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| Abstract: | The E. coli single‐stranded DNA‐binding protein (SSB) binds to the fork DNA helicases RecG and PriA in vitro. Typically for binding to occur, 1.3 m ammonium sulfate must be present, bringing into question the validity of these results as these are nonphysiological conditions. To determine whether SSB can bind to these helicases, we examined binding in vivo. First, using fluorescence microscopy, we show that SSB localizes PriA and RecG to the vicinity of the inner membrane in the absence of DNA damage. Localization requires that SSB be in excess over the DNA helicases and the SSB C‐terminus and both PriA and RecG be present. Second, using the purification of tagged complexes, our results show that SSB binds to PriA and RecG in vivo, in the absence of DNA. We propose that this may be the ‘storage form’ of RecG and PriA. We further propose that when forks stall, RecG and PriA are targeted to the fork by SSB, which, by virtue of its high affinity for single‐stranded DNA, allows these helicases to outcompete other proteins. This ensures their actions in the early stages of the rescue of stalled replication forks. |
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