Metabolite sensing in eukaryotic mRNA biology.

All living creatures change their gene expression program in response to nutrient availability and metabolic demands. Nutrients and metabolites can directly control transcription and activate second-messenger systems. More recent studies reveal that metabolites also affect post-transcriptional regulatory mechanisms. Here, we review the increasing number of connections between metabolism and post-transcriptional regulation in eukaryotic organisms. First, we present evidence that riboswitches, a common mechanism of metabolite sensing in bacteria, also function in eukaryotes. Next, we review an example of a double stranded RNA modifying enzyme that directly interacts with a metabolite, suggesting a link between RNA editing and metabolic state. Finally, we discuss work that shows some metabolic enzymes bind directly to RNA to affect mRNA stability or translation efficiency. These examples were discovered through gene-specific genetic, biochemical, and structural studies. A directed systems level approach will be necessary to determine whether they are anomalies of evolution or pioneer discoveries in what may be a broadly connected network of metabolism and post-transcriptional regulation.