Download MendeleyStructural and biochemical studies of the distinct activity profiles of Rai1 enzymes.
Wang, V.Y., Jiao, X., Kiledjian, M., Tong, L.(2015) Nucleic Acids Res 43: 6596-6606
- PubMed: 26101253
- DOI: https://doi.org/10.1093/nar/gkv620
- Primary Citation of Related Structures:
5BTB, 5BTE, 5BTH, 5BTO, 5BUD - PubMed Abstract:
Recent studies showed that Rai1 and its homologs are a crucial component of the mRNA 5'-end capping quality control mechanism. They can possess RNA 5'-end pyrophosphohydrolase (PPH), decapping, and 5'-3' exonuclease (toward 5' monophosphate RNA) activities, which help to degrade mRNAs with incomplete 5'-end capping. A single active site in the enzyme supports these apparently distinct activities. However, each Rai1 protein studied so far has a unique set of activities, and the molecular basis for these differences are not known. Here, we have characterized the highly diverse activity profiles of Rai1 homologs from a collection of fungal organisms and identified a new activity for these enzymes, 5'-end triphosphonucleotide hydrolase (TPH) instead of PPH activity. Crystal structures of two of these enzymes bound to RNA oligonucleotides reveal differences in the RNA binding modes. Structure-based mutations of these enzymes, changing residues that contact the RNA but are poorly conserved, have substantial effects on their activity, providing a framework to begin to understand the molecular basis for the different activity profiles.
Organizational Affiliation:
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
