Xrn1 is a deNADding enzyme modulating mitochondrial NAD-capped RNA

The cytoplasmic Xrn1 protein has long been established as the predominate 5′ to 3′ exoribonuclease that cleaves RNAs with an unprotected 5′ monophosphate end. Here the authors demonstrate Xrn1 can also degrade RNAs harboring the noncanonical nicotinamide adenine diphosphate (NAD) 5′ cap by removing the NAD cap and degrading the RNA.