A second riboswitch class for the enzyme cofactor NAD.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• A novel bacterial noncoding RNA motif was identified through comparative sequence analysis.
• This motif is almost exclusively associated with pnuC genes.
• PnuC proteins are involved in transporting nicotinamide riboside (NR), a precursor to nicotinamide adenine dinucleotide (NAD+).

Purpose of the Study:

• To investigate the function of the newly discovered "pnuC motif" RNA.
• To determine if these RNAs act as aptamers for NAD+-sensing riboswitches.
• To characterize the binding properties of the RNA motif with NAD+ and related molecules.

Main Methods:

• Comparative sequence analysis to identify conserved RNA motifs.
• Bioinformatic analysis to predict RNA structure and function.
• Biochemical assays to test ligand binding of RNA constructs.

Main Results:

• The "pnuC motif" RNAs were found to selectively bind NAD+, nicotinamide mononucleotide (NMN), and NR.
• Mutations in conserved nucleotides of the motif abolished ligand binding.
• The findings suggest these RNAs function as a second class of NAD+-sensing riboswitches.

Conclusions:

• The "pnuC motif" RNAs represent a novel class of riboswitches.
• These riboswitches regulate gene expression in response to NAD+ levels.
• This discovery expands our understanding of bacterial gene regulation and cofactor sensing.