Editor's Summary
2 February 2006
DNA branches out
Accurate DNA replication is vital to reproduction in all living organisms. Three papers in this issue and a new Web Focus (http://tinyurl.com/e3ecg) present answers to long-standing questions about what goes on at DNA replication forks to ensure this accuracy. Heller and Marians throw light on the fact that even heavily damaged DNA is replicated at high speed. They find that bacterial replication restart systems can prime both leading and lagging DNA strands via DnaG primase. This contradicts the accepted view that leading-strand synthesis is necessarily continuous, and may force a re-evaluation of models for initiation of chromosome replication. Zenkin et al. tackled the mystery of how a short transcript synthesized by RNA polymerase can serve as a primer for DNA replication. The answer lies in a previously unknown transcription elongation complex that may also link DNA replication and transcription machineries. And Lee et al. tackled the matter of how the very different processes taking place on leading and lagging DNA strands are synchronized. As primer synthesis proceeds, DNA primase acts as a molecular brake on the leading-strand polymerase during slow enzymatic steps on the lagging strand.
News and Views: Molecular biology: Prime-time progress
DNA is duplicated within a complex macromolecular machine. Insights into how replication begins and how this is coordinated with progression of DNA synthesis come from a diverse range of sources.
Stephen D. Bell
doi:10.1038/439542a
Article: Replication fork reactivation downstream of a blocked nascent leading strand
Ryan C. Heller and Kenneth J. Marians
doi:10.1038/nature04329
Abstract | Full Text | PDF (335K)
Letter: The mechanism of DNA replication primer synthesis by RNA polymerase
Nikolay Zenkin, Tatyana Naryshkina, Konstantin Kuznedelov and Konstantin Severinov
doi:10.1038/nature04337
First paragraph | Full Text | PDF (220K) | Supplementary information
Letter: DNA primase acts as a molecular brake in DNA replication
Jong-Bong Lee, Richard K. Hite, Samir M. Hamdan, X. Sunney Xie, Charles C. Richardson and Antoine M. van Oijen
doi:10.1038/nature04317
First paragraph | Full Text | PDF (769K) | Supplementary information