Editor's Summary

9 October 2008

Keeping DNA methylation on track


DNA methylation is a key epigenetic process and the faithful maintenance of DNA methylation patterns is essential to the wellbeing of mammalian cells. This means that cells need a mechanism to identify the partially methylated version of CpG once a new DNA strand has been replicated or repaired, so that it can be further methylated by the DNA methyltransferase, DNMT1. As part of this process the protein UHRF1 (or Np95/ICBP90) facilitates the loading of DNMT1 onto the hemimethylated CpG sequences during DNA replication. Three papers in this issue describe crystal structures of the SRA domain of UHRF1 bound to DNA containing a hemi-methylated CpG site. The structures show that methyl-cytosine is flipped out of the DNA helix and inserted into a binding pocket on the SRA domain.

LetterRecognition of hemi-methylated DNA by the SRA protein UHRF1 by a base-flipping mechanism

Kyohei Arita, Mariko Ariyoshi, Hidehito Tochio, Yusuke Nakamura & Masahiro Shirakawa

doi:10.1038/nature07249

LetterStructural basis for recognition of hemi-methylated DNA by the SRA domain of human UHRF1

George V. Avvakumov, John R. Walker, Sheng Xue, Yanjun Li, Shili Duan, Christian Bronner, Cheryl H. Arrowsmith & Sirano Dhe-Paganon

doi:10.1038/nature07273

LetterThe SRA domain of UHRF1 flips 5-methylcytosine out of the DNA helix

Hideharu Hashimoto, John R. Horton, Xing Zhang, Magnolia Bostick, Steven E. Jacobsen & Xiaodong Cheng

doi:10.1038/nature07280