The founding member of this family, XendoU, is a uridylate-specific, divalent cation-dependent enzyme that produces molecules with 2',3'-cyclic phosphate ends [, ]. The human Endou, known as PP11, has endoribonuclease activity with placental tissue specificity [, ].
This EndoU nuclease domain is a bacterial version eukaryotic EndoU nuclease. It is found at the C-terminal region of polymorphic toxin proteins [, ]. Nucleases are widely used as toxins for defense, offense or addiction of selfish elements.
This entry represents the EndoU domain found at the C-terminal of EndoU endoribonucleases, which carries out a conserved RNA processing function. The EndoU domain cleaves RNA at uridylates and release 2',3'-cyclic phosphodiester ends. The EndoU domain is an α/β domain, that contains nine α-helices and three antiparallel β-sheets; the latter are clustered on one side of the domain, whereas the α-helices are largely on the other side []. It contains a conserved trio of catalytic residues, two histidines and a lysine.EndoU is a family of metal-dependent endoribonucleases that is broadly conserved among eukaryotes [, ]. EndoU family members have RNA-binding and endoribonuclease activities and appear to be involved in many aspects ofbiology, including small nucleolar RNA biogenesis, endoplasmic reticulum (ER) network formation, immune response, and neurodegeneration:Xenopus laevis endoribonuclease XendoU is responsible for processing the intron encoded U16 and U86 small nucleolar RNAs (snoRNAs) [, , ].Human EndoU, also known as PP11 (placental protein 11), has an endoribonuclease activity with placental tissue specificity [, , ].Drosophila melanogaster CG2145 and DendoU endoribonucleases [].Caenorhabditis elegans endu-2 regulates nucleotide metabolism and germ cell proliferation in response to nucleotide imbalance and other genotoxic stress [].
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 [, ]. The human EndoU, known as PP11, is a endoribonuclease with placental tissue specificity [].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 [], either upstream or downstream of uridylates, at GUU or GU to produce molecules with 2',3'-cyclic phosphate ends []. PUN RNA is a CoV MDA5-dependent pathogen-associated molecular pattern (PAMP) [].
