Structural basis for Tpt1-catalyzed 2'-PO4 transfer from RNA and NADP(H) to NAD.
Proceedings of the National Academy of Sciences of the United States of America
confidence
Key findings
Structural study of Tpt1-catalyzed 2'-PO4 transfer from RNA and NADP(H) to NAD+; no clinical or biological endpoints reported.
View source on PubMed (PMID 37883434) ↗
- Population
- Archaeal Tpt1 enzymes (in vitro structural study)
- Blinding
- not_reported
- Controls
- none
- Drug class
- coenzyme
Full abstract
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'-PO4 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″-PO4, ADP-ribose-2″-PO4, and 2'-OH RNA, and as substrate complexes with 2',5'-ADP and NAD+, that illuminate 2'-PO4 junction recognition and catalysis. We show that archaeal Tpt1 enzymes can use the 2'-PO4-containing metabolites NADP+ and NADPH as substrates for 2'-PO4 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.