Biology subjects

Nübel, G.

Publications and source records attributed to Nübel, G..

2 recordsLinked to original sources

bioRxiv2020

Extensive 5'-Surveillance Guards Against Non-Canonical NAD-Caps of Nuclear mRNAs in Yeast

The ubiquitous redox coenzyme nicotinamide adenine dinucleotide (NAD) acts as a non-canonical cap structure on prokaryotic and eukaryotic ribonucleic acids. Here we find that in budding yeast, NAD-RNAs are abundant (>1400 species), short (<170 nt), and mostly correspond to mRNA 5-ends. The modification percentage is low (<5%). NAD is incorporated during the initiation step by RNA polymerase II, which uses distinct promoters with a YAAG core motif for this purpose. Most NAD-RNAs are 3-truncated. At least three decapping enzymes, Rai1, Dxo1, and Npy1, guard against NAD-RNA at different cellular locations, targeting overlapping transcript populations. NAD-mRNAs do not support translation in vitro. Our work indicates that in budding yeast, most of the NAD incorporation into RNA seems to be accidental and undesirable to the cell, which has evolved a diverse surveillance machinery to prematurely terminate, decap and reject NAD-RNAs. In BriefIn budding yeast, most of the NAD incorporation into RNA seems to be accidental and undesirable to the cell, which has evolved a diverse surveillance machinery to prematurely terminate, decap and reject NAD-RNAs. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/065920v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@19b86f4org.highwire.dtl.DTLVardef@1b923f3org.highwire.dtl.DTLVardef@1e74f69org.highwire.dtl.DTLVardef@10e787f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIYeast cells have thousands of short NAD-RNAs related to the 5-ends of mRNAs C_LIO_LIRNA polymerase II prefers a YAAG promoter motif for NAD incorporation into RNA C_LIO_LINAD-RNA is strongly guarded against by Rai1, Dxo1, and Npy1 decapping enzymes at different subcellular sites C_LIO_LIIn vitro, NAD-mRNAs are rejected from translation C_LI

cell biology↗

bioRxiv2019

The 5’-NAD cap of RNAIII modulates toxin production in Staphylococcus aureus isolates

1Nicotinamide adenosine dinucleotide (NAD) has been found to be covalently attached to the 5-ends of specific RNAs in many different organisms, but the physiological consequences of this modification are largely unknown. Here we report the occurrence of several NAD-RNAs in the opportunistic human pathogen Staphylococcus aureus. Most prominently, RNAIII, a central quorum-sensing regulator of this bacteriums physiology, was found to be 5-NAD-capped to a significant extent. NAD incorporation efficiency into RNAIII was found to depend in vivo on the -1 position of the P3 promoter. Reduction of RNAIIIs NAD content led to a decreased expression of alpha- and delta-toxins, resulting in reduced cytotoxicity of the modified strains. These effects to not seem to be due to changes in RNAIIIs secondary structure upon NAD attachment, as indicated by largely unaltered patterns in in vitro chemical probing experiments. Our study represents a large step towards establishing a biological function of the 5-NAD cap, which for RNAIII in S. aureus is to modulate the expression of virulence factors.\n\n2 ImportanceNumerous organisms, including bacteria, are endowed with a 5-NAD cap in specific RNAs. While the presence of the 5-NAD cap modulates the stability of the modified RNA species, a significant biological function and phenotype have not been assigned so far. Here, we show the presence of a 5-NAD cap in RNAIII from S. aureus, a dual-function regulatory RNA involved in quorum-sensing processes and regulation of virulence factor expression. We also demonstrate that altering the natural NAD modification ratio of RNAIII leads to a decrease in exotoxin production, thereby modulating bacteriums virulence. Our work unveils a new layer of regulation of RNAIII and the agr system that might be linked to the redox state of the NAD molecule in the cell.

microbiology↗