Helicase homologues maintain cytosine methylation in plants and mammals.

The Arabidopsis DDM1 gene is required for the maintenance of genomic methylation patterns but is a helicase homolog of the SWI2/SNF2 family rather than a DNA methyltransferase. Dennis et al. have shown that disruption of the mouse Lsh gene, the mammalian gene most closely related to DDM1, causes demethylation of the mouse genome. This result suggests that the mechanisms that maintain methylation patterns in the genomes of mammals and flowering plants are more conserved than previously suspected. Copyright 2002 Wiley Periodicals, Inc.