Patterns of chromosomal fragmentation due to uracil-DNA incorporation reveal a novel mechanism of replication-dependent double-stranded breaks

Research output: Contribution to journalArticle

Abstract

There is growing evidence that spontaneous chromosomal fragmentation, one of the main contributors to genetic instability, is intimately linked to DNA replication. In particular, we proposed before that uracil incorporation in DNA triggers chromosomal fragmentation due to replication fork collapse at uracil-excision intermediates. We tested predictions of this model at the chromosomal level in the dut mutants of Escherichia coli, by determining the relationship between DNA replication and patterns of fragmentation in defined chromosomal segments. Here we show that the uracil-DNA-triggered chromosomal fragmentation: (i) has a gradient that parallels the replication gradient, (ii) shows polarity within defined segments pointing towards replication origins and (iii) reorganizes to match induced replication gradients, confirming its dynamic pattern. Unexpectedly, these fragmentation patterns not only support the replication fork collapse model, but also reveal another mechanism of the replication-dependent chromosomal fragmentation triggered by uracil excision.

Original languageEnglish (US)
Pages (from-to)202-215
Number of pages14
JournalMolecular Microbiology
Volume68
Issue number1
DOIs
StatePublished - Apr 1 2008

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

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