5-formylcytosine and 5-carboxylcytosine reduce the rate and substrate specificity of RNA polymerase II transcription.

Although the roles of 5-methylcytosine and 5-hydroxymethylcytosine in epigenetic regulation of gene expression are well established, the functional effects of 5-formylcytosine and 5-carboxylcytosine on the process of transcription are not clear. Here we report a systematic study of the effects of five different forms of cytosine in DNA on mammalian and yeast RNA polymerase II transcription, providing new insights into potential functional interplay between cytosine methylation status and transcription.