Structural basis for the evolution of cyclic phosphodiesterase activity in the U6 snRNA exoribonuclease Usb1
| Autor: | Johanna M Virta, Samuel E. Butcher, Samuel M Hayes, Eric J. Montemayor, Yuichiro Nomura |
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| Rok vydání: | 2019 |
| Předmět: |
Models
Molecular Saccharomyces cerevisiae Proteins Stereochemistry RNA Splicing Saccharomyces cerevisiae Biology Phosphates Evolution Molecular Mitochondrial Proteins Kluyveromyces 03 medical and health sciences 0302 clinical medicine Kluyveromyces marxianus Catalytic Domain RNA Small Nuclear Exoribonuclease Genetics Humans Nucleotide Binding site 030304 developmental biology chemistry.chemical_classification 0303 health sciences Binding Sites Nucleotides Phosphoric Diester Hydrolases Nucleic Acid Enzymes Active site Phosphodiesterase biology.organism_classification chemistry Spliceosomes biology.protein Nucleic Acid Conformation 030217 neurology & neurosurgery |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| Popis: | U6 snRNA undergoes post-transcriptional 3′ end modification prior to incorporation into the active site of spliceosomes. The responsible exoribonuclease is Usb1, which removes nucleotides from the 3′ end of U6 and, in humans, leaves a 2′,3′ cyclic phosphate that is recognized by the Lsm2–8 complex. Saccharomycescerevisiae Usb1 has additional 2′,3′ cyclic phosphodiesterase (CPDase) activity, which converts the cyclic phosphate into a 3′ phosphate group. Here we investigate the molecular basis for the evolution of Usb1 CPDase activity. We examine the structure and function of Usb1 from Kluyveromyces marxianus, which shares 25 and 19% sequence identity to the S. cerevisiae and Homo sapiens orthologs of Usb1, respectively. We show that K. marxianus Usb1 enzyme has CPDase activity and determined its structure, free and bound to the substrate analog uridine 5′-monophosphate. We find that the origin of CPDase activity is related to a loop structure that is conserved in yeast and forms a distinct penultimate (n – 1) nucleotide binding site. These data provide structural and mechanistic insight into the evolutionary divergence of Usb1 catalysis. |
| Databáze: | OpenAIRE |
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