Dynamic DNA-bound PCNA complexes co-ordinate Okazaki fragment synthesis, processing and ligation. Issue 24 (4th December 2020)

• Record Type: Journal Article
• Authors: Matsumoto, Yoshihiro; Brooks, Rhys C.; Sverzhinsky, Aleksandr; Pascal, John M.; Tomkinson, Alan E.
• Is Part Of: Journal of molecular biology. Volume 432:Issue 24(2020)
• Publication Date: 2020-12-04
• Subjects: DNA replication -- DNA synthesis -- DNA flap cleavage -- DNA ligation -- DNA-protein complex; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2020.10.032
• Languages: English
• ISSNs: 0022-2836

Abstract

Graphical abstract: Highlights: How does PCNA co-ordinate Okazaki fragment synthesis, processing and ligation? Physical and functional interaction between DNA polymerase δ and DNA ligase I. Both DNA ligase I and FEN1 associate with DNA polymerase δ-PCNA during gap filling DNA synthesis. A double-dumbbell complex of DNA ligase I and PCNA remains on the ligated DNA. Dynamic PCNA complexes co-ordinate Okazaki fragment synthesis, processing and ligation. Abstract: More than a million Okazaki fragments are synthesized, processed and joined during replication of the human genome. After synthesis of an RNA-DNA oligonucleotide by DNA polymerase α holoenzyme, proliferating cell nuclear antigen (PCNA), a homotrimeric DNA sliding clamp and polymerase processivity factor, is loaded onto the primer-template junction by replication factor C (RFC). Although PCNA interacts with the enzymes DNA polymerase δ (Pol δ), flap endonuclease 1 (FEN1) and DNA ligase I (LigI) that complete Okazaki fragment processing and joining, it is not known how the activities of these enzymes are coordinated. Here we describe a novel interaction between Pol δ and LigI that is critical for Okazaki fragment joining in vitro. Both LigI and FEN1 associate with PCNA-Pol δ during gap-filling synthesis, suggesting that gap-filling synthesis is carried out by a complex of PCNA, Pol δ, FEN1 and LigI. Following ligation, PCNA and LigI remain on the DNA, indicating that Pol δ and FEN1 dissociate during 5′ end processing and that LigI engages PCNA at the DNA nick generated by FEN1 and Pol δ. Thus, dynamic PCNA complexes coordinate Okazaki fragment synthesis and processing with PCNA and LigI forming a terminal structure of two linked protein rings encircling the ligated DNA.