Interactive Roles of DNA Helicases and Translocases with the Single-Stranded DNA Binding Protein RPA in Nucleic Acid Metabolism

Abstract

Helicases and translocases use the energy of nucleoside triphosphate binding and hydrolysis to unwind/resolve structured nucleic acids or move along a single-stranded or double-stranded polynucleotide chain, respectively. These molecular motors facilitate a variety of transactions including replication, DNA repair, recombination, and transcription. A key partner of eukaryotic DNA helicases/translocases is the single-stranded DNA binding protein Replication Protein A (RPA). Biochemical, genetic, and cell biological assays have demonstrated that RPA interacts with these human molecular motors physically and functionally, and their association is enriched in cells undergoing replication stress. The roles of DNA helicases/translocases are orchestrated with RPA in pathways of nucleic acid metabolism. RPA stimulates helicase-catalyzed DNA unwinding, enlists translocases to sites of action, and modulates their activities in DNA repair, fork remodeling, checkpoint activation, and telomere maintenance. The dynamic interplay between DNA helicases/translocases and RPA is just beginning to be understood at the molecular and cellular levels, and there is still much to be learned, which may inform potential therapeutic strategies.

Cas3 Protein—A Review of a Multi-Tasking Machine

“…Cas3 loads onto ssDNA and translocates it using ATP-hydrolysis [36]. In this way it can separate DNA duplex strands as a helicase, and may also be able to displace other DNA binding proteins during translocation, similarly to other translocases [36][37][38][39]. After initial DNA nicking by Cas3 HD-nuclease, Cas3 translocates DNA with 3' to 5' directionality generating ssDNA gaps from a Cascade-R-loop formed on duplex DNA, which is detectable in single-molecule experiments using GFP-RPA [27].…”

RecQ and Fe–S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions

“…The single-stranded DNA-binding protein Replication Protein A (RPA) is a partner of both RecQ and Fe–S helicases that greatly enhances DNA unwinding by these lowly processive helicases [160]. Protein mapping and biochemical studies demonstrated that the physical interaction of WRN with RPA is required for stimulation of helicase-catalyzed DNA unwinding activity [161]; this is probably true for the other RecQ and Fe–S helicases based on observations that heterologous single-stranded binding proteins poorly stimulate their unwinding activities.…”

G Protein-Coupled Receptor Systems as Crucial Regulators of DNA Damage Response Processes

“…As life proceeds through the individual’s aging process, both endogenous (e.g., reactive oxygen species (ROS)) and environmental (e.g., ionizing radiation) stressors are constantly attacking DNA, causing structural damage [ 9 ]. Unrepaired DNA damage negatively affects genome replication and transcription, causing wide-scale chromosomal aberrations that disrupt critical cell functions such as energy metabolism and protein folding/management [ 19 , 20 , 21 ]. Given the importance of DNA-protective activity as an anti-aging strategy, coupled to the feasibility of GPCR druggability, the generation of GPCR-based DDR controlling agents holds considerable promise for improved treatments for both disorders of genomic aging such as Werner syndrome or ataxia-telangiectasia, as well as age-related disorders such as metabolic syndrome or Parkinson’s disease.…”