Identification of an RNase J ortholog in Sulfolobus solfataricus: implications for 5'-to-3' directional decay and 5'-end protection of mRNA in Crenarchaeota

RNA. 2011 Jan;17(1):99-107. doi: 10.1261/rna.2418211. Epub 2010 Nov 29.


In both Bacteria and Eukaryotes, degradation is known to start at the 5' and at the 3' extremities of mRNAs. Until the recent discovery of 5'-to-3' exoribonucleases in hyperthermophilic Euryarchaeota, the exosome was assumed to be the key enzyme in mRNA degradation in Archaea. By means of zymogram assays and bioinformatics, we have identified a 5'-to-3' exoribonuclease activity in the crenarchaeum Sulfolobus solfataricus (Sso), which is affected by the phosphorylation state of the 5'-end of the mRNA. The protein comprises typical signature motifs of the β-CASP family of metallo-β-lactamases and was termed Sso-RNAse J. Thus, our study provides the first evidence for a 5'-to-3' directional mRNA decay pathway in the crenarchaeal clade of Archaea. In Bacteria the 5'-end of mRNAs is often protected by a tri-phosphorylated 5'-terminus and/or by stem-loop structures, while in Eukaryotes the cap-binding complex is responsible for this task. Here, we show that binding of translation initiation factor a/eIF2(γ) to the 5'-end of mRNA counteracts the 5'-to-3' exoribonucleolytic activity of Sso-RNase J in vitro. Hence, 5'-to-3' directional decay and 5'-end protection appear to be conserved features of mRNA turnover in all kingdoms of life.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Eukaryotic Initiation Factor-2 / genetics
  • Eukaryotic Initiation Factor-2 / metabolism
  • Phosphorylation
  • Protein Binding
  • RNA, Bacterial / genetics*
  • RNA, Bacterial / metabolism
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism
  • Ribonucleases / chemistry*
  • Ribonucleases / genetics
  • Ribonucleases / metabolism*
  • Ribosomes / metabolism
  • Sulfolobus solfataricus / enzymology*
  • Sulfolobus solfataricus / genetics


  • Eukaryotic Initiation Factor-2
  • RNA, Bacterial
  • RNA, Messenger
  • Ribonucleases