Near-continuously synthesized leading strands in Escherichia coli are broken by ribonucleotide excision.

ABSTRACT: In vitro, purified replisomes drive model replication forks to synthesize continuous leading strands, even without ligase, supporting the semidiscontinuous model of DNA replication. However, nascent replication intermediates isolated from ligase-deficient Escherichia coli comprise only short (on average 1.2-kb) Okazaki fragments. It was long suspected that cells replicate their chromosomal DNA by the semidiscontinuous mode observed in vitro but that, in vivo, the nascent leading strand was artifactually fragmented postsynthesis by excision repair. Here, using high-resolution separation of pulse-labeled replication intermediates coupled with strand-specific hybridization, we show that excision-proficient E. coli generates leading-strand intermediates >10-fold longer than laggi

SUBMITTER: Cronan GE 

PROVIDER: S-EPMC6347710 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature