Abstract
In the mom1 mutants of Arabidopsis, silent multicopy transgenes and pericentromeric repeats are transcriptionally activated. The mom1 mutants, in contrast to the ddm1 and met1 mutants, show no reduction in genome-wide DNA methylation and no developmental abnormalities. However, we have recently found that transcripts derived from endogenous genes encoding functional proteins are accumulated in the mom1 mutants. We are currently analyzing the details of the transcripts and DNA methylation status of one of these genes.
The MOM1 gene encodes a 220kD nuclear protein that shows a partial similarity to the ATPase region of the SWI2/SNF2-type chromatin remodeling proteins of animals, but it is unlikely that the MOM1 protein is a chromatin remodeling protein by itself. In rice genome, there are two genes encoding MOM1-like proteins and these putative rice MOM1 proteins carry chromodomains that may interact with other factors to maintain the silent state.
