8TG3

Structural basis for Tpt1-catalyzed 2'-PO 4 transfer from RNA and NADP(H) to NAD.

(2023) Proc Natl Acad Sci U S A 120: e2312999120-e2312999120

• PubMed: 37883434 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1073/pnas.2312999120
• Primary Citation of Related Structures:  
  8TFI, 8TFX, 8TFY, 8TFZ, 8TG3, 8TG4, 8TG5, 8TG6


• PubMed 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'-PO ₄ 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 ₄ , ADP-ribose-2″-PO ₄ , and 2'-OH RNA, and as substrate complexes with 2',5'-ADP and NAD ⁺ , that illuminate 2'-PO ₄ junction recognition and catalysis. We show that archaeal Tpt1 enzymes can use the 2'-PO ₄ -containing metabolites NADP ⁺ and NADPH as substrates for 2'-PO ₄ 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.

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Organizational Affiliation: 

Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065.