title: Mechanochemical regulations of RPA's binding to ssDNA.
abstract: Replication protein A (RPA) is a ubiquitous eukaryotic single-stranded DNA (ssDNA) binding protein that serves to protect ssDNA from degradation and annealing, and as a template for recruitment of many downstream factors in virtually all DNA transactions in cell. During many of these transactions, DNA is tethered and is likely subject to force. Previous studies of RPA's binding behavior on ssDNA were conducted in the absence of force; therefore the RPA-ssDNA conformations regulated by force remain unclear. Here, using a combination of atomic force microscopy imaging and mechanical manipulation of single ssDNA tethers, we show that force mediates a switch of the RPA bound ssDNA from amorphous aggregation to a much more regular extended conformation. Further, we found an interesting non-monotonic dependence of the binding affinity on monovalent salt concentration in the presence of force. In addition, we discovered that zinc in micromolar concentrations drives ssDNA to a unique, highly stiff and more compact state. These results provide new mechanochemical insights into the influences and the mechanisms of action of RPA on large single ssDNA.
authors: 1] Mechanobiology Institute, National University of Singapore, 117411 Singapore [2] Department of Physics, National University of Singapore, 117542 Singapore.
authors: Jin
authors: J
authors: Chen
authors: Mechanobiology Institute, National University of Singapore, 117411 Singapore.
authors: Shimin
authors: S
authors: Le
authors: Departments of Biochemistry and Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
authors: Anindita
authors: A
authors: Basu
authors: Departments of Biochemistry and Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
authors: Walter J
authors: WJ
authors: Chazin
authors: 1] Mechanobiology Institute, National University of Singapore, 117411 Singapore [2] Department of Physics, National University of Singapore, 117542 Singapore [3] Centre for Bioimaging Sciences, National University of Singapore, 117546 Singapore.
authors: Jie
authors: J
authors: Yan
mesh_terms: D001696:Biomechanical Phenomena; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D011485:Protein Binding / Q000187:drug effects; D051716:Replication Protein A / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D004277:DNA, Single-Stranded; D051716:Replication Protein A; D012965:Sodium Chloride