Structure of tRNA splicing enzyme Tpt1 illuminates the mechanism of RNA 2′-PO4 recognition and ADP-ribosylation

Ankan Banerjee, Annum Munir, Leonora Abdullahu, Masad J. Damha, Yehuda Goldgur, Stewart Shuman
2019 Nature Communications  
Tpt1 is an essential agent of fungal tRNA splicing that removes the 2′-PO 4 at the splice junction generated by fungal tRNA ligase. Tpt1 catalyzes a unique two-step reaction whereby the 2′-PO 4 attacks NAD + to form an RNA-2′-phospho-ADP-ribosyl intermediate that undergoes transesterification to yield 2′-OH RNA and ADP-ribose-1″,2″-cyclic phosphate products. Because Tpt1 is inessential in exemplary bacterial and mammalian taxa, Tpt1 is seen as an attractive antifungal target. Here we report a
more » ... 4 Å crystal structure of Tpt1 in a productmimetic complex with ADP-ribose-1″-phosphate in the NAD + site and pAp in the RNA site. The structure reveals how Tpt1 recognizes a 2′-PO 4 RNA splice junction and the mechanism of RNA phospho-ADP-ribosylation. This study also provides evidence that a bacterium has an endogenous phosphorylated substrate with which Tpt1 reacts.
doi:10.1038/s41467-018-08211-9 fatcat:3d4flocpufcl7fhrdn5dezkciu