8rk2
Human Replication protein A (RPA; trimeric core) - ssDNA complex
Structural highlights
FunctionRFA1_HUMAN Plays an essential role in several cellular processes in DNA metabolism including replication, recombination and DNA repair. Binds and subsequently stabilizes single-stranded DNA intermediates and thus prevents complementary DNA from reannealing.[1] [2] Functions as component of the alternative replication protein A complex (aRPA). aRPA binds single-stranded DNA and probably plays a role in DNA repair; it does not support chromosomal DNA replication and cell cycle progression through S-phase. In vitro, aRPA cannot promote efficient priming by DNA polymerase alpha but supports DNA polymerase delta synthesis in the presence of PCNA and replication factor C (RFC), the dual incision/excision reaction of nucleotide excision repair and RAD51-dependent strand exchange.[3] [4] Publication Abstract from PubMedRAD52 is important for the repair of DNA double-stranded breaks(1,2), mitotic DNA synthesis(3-5) and alternative telomere length maintenance(6,7). Central to these functions, RAD52 promotes the annealing of complementary single-stranded DNA (ssDNA)(8,9) and provides an alternative to BRCA2/RAD51-dependent homologous recombination repair(10). Inactivation of RAD52 in homologous-recombination-deficient BRCA1- or BRCA2-defective cells is synthetically lethal(11,12), and aberrant expression of RAD52 is associated with poor cancer prognosis(13,14). As a consequence, RAD52 is an attractive therapeutic target against homologous-recombination-deficient breast, ovarian and prostate cancers(15-17). Here we describe the structure of RAD52 and define the mechanism of annealing. As reported previously(18-20), RAD52 forms undecameric (11-subunit) ring structures, but these rings do not represent the active form of the enzyme. Instead, cryo-electron microscopy and biochemical analyses revealed that ssDNA annealing is driven by RAD52 open rings in association with replication protein-A (RPA). Atomic models of the RAD52-ssDNA complex show that ssDNA sits in a positively charged channel around the ring. Annealing is driven by the RAD52 N-terminal domains, whereas the C-terminal regions modulate the open-ring conformation and RPA interaction. RPA associates with RAD52 at the site of ring opening with critical interactions occurring between the RPA-interacting domain of RAD52 and the winged helix domain of RPA2. Our studies provide structural snapshots throughout the annealing process and define the molecular mechanism of ssDNA annealing by the RAD52-RPA complex. Mechanism of single-stranded DNA annealing by RAD52-RPA complex.,Liang CC, Greenhough LA, Masino L, Maslen S, Bajrami I, Tuppi M, Skehel M, Taylor IA, West SC Nature. 2024 Apr 24. doi: 10.1038/s41586-024-07347-7. PMID:38658755[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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