InterPro domain: IPR037227

This entry represents the EndoU-like endoribonucleases from a variety of organisms that range from viruses to humans. The founding member XendoU is a uridylate-specific, divalent cation-dependent enzyme that produces molecules with 2',3'-cyclic phosphate ends [ 1 , 2 ]. The human EndoU, known as PP11, is a endoribonuclease with placental tissue specificity [ 3 ].

In human SARS coronavirus, EndoU (also known as NSP15) is part of the replicase-transcriptase complex that plays important roles in virus replication and transcription. NSP15 is a Uridylate-specific endoribonuclease that cleaves the 5'-polyuridines from negative-sense viral RNA, termed PUN RNA [ 4 ], either upstream or downstream of uridylates, at GUU or GU to produce molecules with 2',3'-cyclic phosphate ends [ 5 ]. PUN RNA is a CoV MDA5-dependent pathogen-associated molecular pattern (PAMP) [ 6 ].

1. Functional characterization of XendoU, the endoribonuclease involved in small nucleolar RNA biosynthesis. J. Biol. Chem. 280, 18996-9002
2. The structure of the endoribonuclease XendoU: From small nucleolar RNA processing to severe acute respiratory syndrome coronavirus replication. Proc. Natl. Acad. Sci. U.S.A. 103, 12365-70
3. The tumor marker human placental protein 11 is an endoribonuclease. J. Biol. Chem. 283, 34712-9
4. Coronavirus endoribonuclease targets viral polyuridine sequences to evade activating host sensors. Proc. Natl. Acad. Sci. U.S.A.
5. Embryonic expression patterns of Eukaryotic EndoU ribonuclease family gene endouC in zebrafish. Gene Expr. Patterns 25-26, 66-70