Structure of tRNA splicing enzyme Tpt1 illuminates the mechanism of RNA 2'-PO recognition and ADP-ribosylation.

Publication Type:

Journal Article


Nat Commun, Volume 10, Issue 1, p.218 (2019)


<p>Tpt1 is an essential agent of fungal tRNA splicing that removes the 2&#39;-PO at the splice junction generated by fungal tRNA ligase. Tpt1 catalyzes a unique two-step reaction whereby the 2&#39;-PO attacks NAD to form an RNA-2&#39;-phospho-ADP-ribosyl intermediate that undergoes transesterification to yield 2&#39;-OH RNA and ADP-ribose-1&Prime;,2&Prime;-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 1.4&thinsp;Å crystal structure of Tpt1 in a product-mimetic complex with ADP-ribose-1&Prime;-phosphate in the NAD site and pAp in the RNA site. The structure reveals how Tpt1 recognizes a 2&#39;-PO 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.</p>

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