5t16
From Proteopedia
Crystal structure of yeast RNase III (Rnt1p) complexed with a non-hydrolyzable RNA substrate analog
Structural highlights
FunctionRNT1_YEAST DsRNA-specific nuclease that cleaves eukaryotic pre-ribosomal RNA at the U3 snoRNP-dependent A0 site in the 5'-external transcribed spacer (ETS) and in the 3'-ETS. In vitro, cleaves synthetic 5'-ETS RNA A0 site in the absence of snoRNA or other factors. Has an essential growth function in addition to pre-rRNA processing. Publication Abstract from PubMedDouble-stranded RNA (dsRNA)-specific RNase III proteins are required for RNA maturation and gene regulation. The mechanism of prokaryotic RNase IIIs has been well characterized, but how eukaryotic RNase IIIs (exemplified by Rnt1p, Drosha, and Dicer) work is less clear. Recently, we reported the crystal structure of Rnt1p in complex with RNA, revealing a double-ruler mechanism for substrate selection. Here, we present more structures of Rnt1p, either RNA free or RNA bound, featuring two major conformations of the enzyme. Using these structures with existing data, we describe the functional cycle of Rnt1p in five steps, selecting, loading, locking, cleavage, and releasing. We also describe atomic details of the two-Mg2+-ion catalytic mechanism that is applicable to all eukaryotic RNase III enzymes. Overall, our results indicate that substrate selection is achieved independent of cleavage, allowing the recognition of substrates with different structures while preserving the basic mechanism of cleavage. The Functional Cycle of Rnt1p: Five Consecutive Steps of Double-Stranded RNA Processing by a Eukaryotic RNase III.,Song H, Fang X, Jin L, Shaw GX, Wang YX, Ji X Structure. 2017 Feb 7;25(2):353-363. doi: 10.1016/j.str.2016.12.013. Epub 2017, Jan 19. PMID:28111020[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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