{"title":"Structures of RNA phosphotransferase Tpt1 reveal distinct binding modes for an RNA 2'-PO<sub>4</sub> splice junction versus a 5'-PO<sub>4</sub> mononucleotide.","authors":"Agata Jacewicz, Masad J Damha, Stewart Shuman","doi":"10.1261/rna.080444.125","DOIUrl":null,"url":null,"abstract":"<p><p>Tpt1 is a widely distributed enzyme that removes an internal RNA 2'-phosphate by transfer to NAD<sup>+</sup>, via a two-step reaction in which: (i) the RNA 2'-PO<sub>4</sub> attacks NAD<sup>+</sup> to form an RNA-2'-phospho-(ADP-ribose) intermediate and expel nicotinamide; and (ii) the ADP-ribose O2″ attacks the RNA 2'-phosphodiester to form 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate products. Tpt1 can also execute a single-step ADP-ribosyltransferase reaction at a 5'-monophosphate nucleic acid terminus that installs a 5'-phospho-ADP-ribose cap structure. Here we present crystal structures of Tpt1 bound to an RNA containing an internal 2'-PO<sub>4</sub> mark (the substrate for the canonical Tpt1 pathway) and in a complex with 5'-AMP. We find that Tpt1 has distinct binding modes, whereby the RNA 2'-PO<sub>4</sub> and the AMP 5'-PO<sub>4</sub> are engaged by the same set of active site amino acids, but the 2'-PO<sub>4</sub> nucleoside and the 5'-nucleoside occupy different sites on the enzyme.</p>","PeriodicalId":21401,"journal":{"name":"RNA","volume":" ","pages":"916-922"},"PeriodicalIF":5.0000,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12170183/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"RNA","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1261/rna.080444.125","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Tpt1 is a widely distributed enzyme that removes an internal RNA 2'-phosphate by transfer to NAD+, via a two-step reaction in which: (i) the RNA 2'-PO4 attacks NAD+ to form an RNA-2'-phospho-(ADP-ribose) intermediate and expel nicotinamide; and (ii) the ADP-ribose O2″ attacks the RNA 2'-phosphodiester to form 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate products. Tpt1 can also execute a single-step ADP-ribosyltransferase reaction at a 5'-monophosphate nucleic acid terminus that installs a 5'-phospho-ADP-ribose cap structure. Here we present crystal structures of Tpt1 bound to an RNA containing an internal 2'-PO4 mark (the substrate for the canonical Tpt1 pathway) and in a complex with 5'-AMP. We find that Tpt1 has distinct binding modes, whereby the RNA 2'-PO4 and the AMP 5'-PO4 are engaged by the same set of active site amino acids, but the 2'-PO4 nucleoside and the 5'-nucleoside occupy different sites on the enzyme.
期刊介绍:
RNA is a monthly journal which provides rapid publication of significant original research in all areas of RNA structure and function in eukaryotic, prokaryotic, and viral systems. It covers a broad range of subjects in RNA research, including: structural analysis by biochemical or biophysical means; mRNA structure, function and biogenesis; alternative processing: cis-acting elements and trans-acting factors; ribosome structure and function; translational control; RNA catalysis; tRNA structure, function, biogenesis and identity; RNA editing; rRNA structure, function and biogenesis; RNA transport and localization; regulatory RNAs; large and small RNP structure, function and biogenesis; viral RNA metabolism; RNA stability and turnover; in vitro evolution; and RNA chemistry.