Study On The Dynamic Regulation Mechanism Of Human RPA Protein On Single-stranded DNA Structure From The Single Molecule Level

Replication protein A(RPA)is the major eukaryotic single-stranded DNA(ssDNA)binding protein with essential roles in genome maintenance.It has a high affinity with single-stranded DNA,and it interacts with other related proteins to protect ssDNA from nuclease degRadation and direct metabolism-related proteins into corresponding positions.Human replication protein A(RPA)plays a very important role in DNA replication,homologous recombination and nucleotide excision repair.RPA is a heterologous triploid protein,which has three major binding modes to ssDNA: 8-10 nt binding mode,12-23 nt binding mode and 28-30 nt binding mode.recent studies suggested that RPA-ssDNA interaction is dynamic.However,how RPA navigates between different modes and remodifies ssDNA structure in the dynamic process are still unknown.The topic used single-molecule FRET to systematically investigate the interaction between human RPA and ssDNA.The topic show that:1? RPA protects different lengths of ssDNA with different modes and ssDNA can be either straightened or bent.2 ? RPA dynamically switches between those modes with different dwell times.3 ? at high concentrations,RPA densely coated ssDNA in a novel compact mode,generating a static DNA filament.4?The topic examined the interplay between RPA and Rad51 on ssDNA.Although they cannot significantly displace each other,free RPA may attenuate the stability of Rad51-ssDNA filaments during homologous recombination.This study provides new insight into the rich dynamics of RPA in DNA processing pathways,and highlights the adaptability of RPA to protect ssDNA in various situations.