Cryo-EM structure of the replisome reveals multiple interactions coordinating DNA synthesis

Abstract

We present a structure of the similar to 650-kDa functional replisome of bacteriophage T7 assembled on DNA resembling a replication fork. A structure of the complex consisting of six domains of DNA helicase, five domains of RNA primase, two DNA polymerases, and two thioredoxin (processivity factor) molecules was determined by single-particle cryo-electron microscopy. The two molecules of DNA polymerase adopt a different spatial arrangement at the replication fork, reflecting their roles in leading-and lagging-strand synthesis. The structure, in combination with biochemical data, reveals molecular mechanisms for coordination of leading-and lagging-strand synthesis. Because mechanisms of DNA replication are highly conserved, the observations are relevant to other replication systems.