6n6j
Human REXO2 bound to pAA
Structural highlights
FunctionORN_HUMAN 3'-to-5' exoribonuclease specific for small oligoribonucleotides. Active on small (primarily </=5 nucleotides in length) single-stranded RNA and DNA oligomers. May have a role in cellular nucleotide recycling.[1] Publication Abstract from PubMedDegradation of RNA polymers, an ubiquitous process in all cells, is catalyzed by specific subsets of endo- and exoribonucleases that together recycle RNA fragments into nucleotide monophosphate. In gamma-proteobacteria, 3-'5' exoribonucleases comprise up to eight distinct enzymes. Among them, Oligoribonuclease (Orn) is unique as its activity is required for clearing short RNA fragments, which is important for cellular fitness. However, the molecular basis of Orn's unique cellular function remained unclear. Here, we show that Orn exhibits exquisite substrate preference for diribonucleotides. Crystal structures of substrate-bound Orn reveal an active site optimized for diribonucleotides. While other cellular RNases process oligoribonucleotides down to diribonucleotide entities, Orn is the one and only diribonucleotidase that completes the terminal step of RNA degradation. Together, our studies indicate RNA degradation as a step-wise process with a dedicated enzyme for the clearance of a specific intermediate pool, diribonucleotides, that affects cellular physiology and viability. A dedicated diribonucleotidase resolves a key bottleneck for the terminal step of RNA degradation.,Kim SK, Lormand JD, Weiss CA, Eger KA, Turdiev H, Turdiev A, Winkler WC, Sondermann H, Lee VT Elife. 2019 Jun 21;8. pii: 46313. doi: 10.7554/eLife.46313. PMID:31225796[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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