Transcriptional gene silencing (TGS) is often associated with an increased level of
cytosine methylation in the affected promoters. The effect of methylation of the cauliflower
mosaic virus (CaMV) 35S promoter sequence on its binding to factors present in the
nuclei was analyzed by electrophoretic mobility shift assays using extracts of petunia
flowers. Specific DNA‐protein interactions were detected in the region of the CaMV
35S promoter that contains the as‐1 element and the region between - 345 and - 208. The binding of protein factor(s)
to the as‐1 element was influenced by cytosine methylation, whereas the binding to the region
between - 345 and - 208 was unaffected. The results suggest that cytosine methylation
of the as-1 element potentially affects the activity of the CaMV 35S promoter.
Cauliflower mosaic virus 35S promoter - cytosine methylation - DNA-protein interaction
- electrophoretic mobility shift assay - transcriptional gene silencing