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Low-molecular-weight DNA replication intermediates in Escherichia coli: mechanism of formation and strand specificity.

ABSTRACT: Chromosomal DNA replication intermediates, revealed in ligase-deficient conditions in vivo, are of low molecular weight (LMW) independently of the organism, suggesting discontinuous replication of both the leading and the lagging DNA strands. Yet, in vitro experiments with purified enzymes replicating sigma-structured substrates show continuous synthesis of the leading DNA strand in complete absence of ligase, supporting the textbook model of semi-discontinuous DNA replication. The discrepancy between the in vivo and in vitro results is rationalized by proposing that various excision repair events nick continuously synthesized leading strands after synthesis, producing the observed LMW intermediates. Here, we show that, in an Escherichia coli ligase-deficient strain with all known excision repair pathways inactivated, new DNA is still synthesized discontinuously. Furthermore, hybridization to strand-specific targets demonstrates that the LMW replication intermediates come from both the lagging and the leading strands. These results support the model of discontinuous leading strand synthesis in E. coli.

SUBMITTER: Amado L

PROVIDER: S-EPMC3812275 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Low-molecular-weight DNA replication intermediates in Escherichia coli: mechanism of formation and strand specificity.

Amado Luciana L Kuzminov Andrei A

Journal of molecular biology 20130720 22

Chromosomal DNA replication intermediates, revealed in ligase-deficient conditions in vivo, are of low molecular weight (LMW) independently of the organism, suggesting discontinuous replication of both the leading and the lagging DNA strands. Yet, in vitro experiments with purified enzymes replicating sigma-structured substrates show continuous synthesis of the leading DNA strand in complete absence of ligase, supporting the textbook model of semi-discontinuous DNA replication. The discrepancy b ...[more]

PMID: 23876705

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Dataset Information

Low-molecular-weight DNA replication intermediates in Escherichia coli: mechanism of formation and strand specificity.

Publications

Low-molecular-weight DNA replication intermediates in Escherichia coli: mechanism of formation and strand specificity.

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