Structural basis for Tpt1-catalyzed 2'-PO transfer from RNA and NADP(H) to NAD.
Publication Type:
Journal ArticleSource:
Proc Natl Acad Sci U S A, Volume 120, Issue 44, p.e2312999120 (2023)Keywords:
Adenosine Diphosphate Ribose, NAD, NADP, Phosphates, RNA, RNA, TransferAbstract:
<p>Tpt1 is an essential agent of fungal and plant tRNA splicing that removes an internal RNA 2'-phosphate generated by tRNA ligase. Tpt1 also removes the 2'-phosphouridine mark installed by Ark1 kinase in the V-loop of archaeal tRNAs. Tpt1 performs a two-step reaction in which the 2'-PO attacks NAD to form an RNA-2'-phospho-(ADP-ribose) intermediate, and transesterification of the ADP-ribose O2″ to the RNA 2'-phosphodiester yields 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate. Here, we present structures of archaeal Tpt1 enzymes, captured as product complexes with ADP-ribose-1″-PO, ADP-ribose-2″-PO, and 2'-OH RNA, and as substrate complexes with 2',5'-ADP and NAD, that illuminate 2'-PO junction recognition and catalysis. We show that archaeal Tpt1 enzymes can use the 2'-PO-containing metabolites NADP and NADPH as substrates for 2'-PO transfer to NAD. A role in 2'-phospho-NADP(H) dynamics provides a rationale for the prevalence of Tpt1 in taxa that lack a capacity for internal RNA 2'-phosphorylation.</p>