Identification of NAD+ capped mRNAs in Saccharomyces cerevisiae

RNAs besides tRNA and rRNA contain chemical modifications, including the recently described 5′ nicotinamide-adenine dinucleotide (NAD + ) RNA in bacteria. Whether 5′ NAD-RNA exists in eukaryotes remains unknown. We demonstrate that 5′ NAD-RNA is found on subsets of nuclear and mitochondrial encoded mRNAs in Saccharomyces cerevisiae . NAD-mRNA appears to be produced cotranscriptionally because NAD-RNA is also found on pre-mRNAs, and only on mitochondrial transcripts that are not 5′ end processed. These results define an additional 5′ RNA cap structure in eukaryotes and raise the possibility that this 5′ NAD + cap could modulate RNA stability and translation on specific subclasses of mRNAs.