Chemistry

RNA polymerase

Enzyme

Cofactor

RNA editing

Nicotinamide adenine dinucleotide

Polymerase

Non-coding RNA

Gene

Transcription (linguistics)

NAD+ kinase

Cell biology

Nucleotide

Biology

Linguistics

Philosophy

Biochemistry

Nature

RNA caps other than the 7-methylguanylate modification are generated by a distinct mechanism in which caps are added during, not after, transcription initiation through the use of non-canonical initiating nucleotides by RNA polymerases, a finding which has functional consequences. To prevent degradation, both ends of messenger RNAs are modified to block nucleases. Until recently, the only modification known to protect the 5' end was a 7-methylguanylate 'cap', although it has been found that some mRNAs use NAD+ or dpCoA instead. It has been assumed that the mechanism of addition of these alternative caps would be the same. However, Bryce Nickels and colleagues now show that alternative caps use a distinct mechanism, by which they are incorporated during, not after, transcription initiation. In both bacterial and eukaryotic cells, RNA polymerase uses these moieties as non-canonical initiating nucleotides, and their use has functional consequences. The chemical nature of the 5′ end of RNA is a key determinant of...

The mechanism of RNA 5′ capping with NAD+, NADH and desphospho-CoA