Work

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

Year: 2019

Type: article

Abstract: Significance The antiparallel orientation of strands in a DNA duplex and unidirectional polarity of DNA polymerases necessitate that replication forks operate semidiscontinuously. That is, the strand replicated codirectionally to replication-fork movement, termed the “leading” strand, is synthesized continuously, while the oppositely oriented “lagging” strand is synthesized in short “Okazaki” fragments, later joined by ligase. Semidiscontinuous replication is observed in vitro, even in reactions lacking ligase. However, in vivo, in ligase ( lig ) mutants, nascent DNA from both strands is found only in small pieces. Here, we report the continuous synthesis of leading strands in lig mutant Escherichia coli lacking all DNA excision-repair activities and, using an improved sucrose-gradient system, identify misincorporated ribonucleotides as the major driver of leading-strand fragmentation.

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.1814512116

Authors: Glen E. Cronan, Elena A. Kouzminova, Andrei Kuzminov

Institution: University of Illinois Urbana-Champaign

Language: English

Topic: DNA Repair Mechanisms

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: bronze

Funders: National Institutes of Health, National Institute of General Medical Sciences, Office of Extramural Research, National Institutes of Health

Awards: Chromosomal death due to misincorporation of wrong material into DNA, G4339611208, G6553004658