ART Database

A family of ADP-ribosyltransferases found in eukaryotes, bacteria and archaeons. Modifies nucleic acids (tRNA).

This entry includes Tpt1 and its homologues from all domains of life. Tpt1 was first discovered as an essential component of the fungal tRNA splicing pathway, which characteristically generates a 2'-PO4, 3'-5' phosphodiester splice junction during the tRNA ligation reaction [PUBMED:2154680]. It is an enzyme that catalyzes the transfer of an internal RNA 2'-monophosphate (2'-PO4) to NAD+ to form a 2'-OH RNA, ADP-ribose 1"-2" cyclic phosphate, and nicotinamide [PUBMED:8392224]. Interestingly, many Tpt1 homologues have no obvious need for an RNA 2'-phosphotransferase because: (i) they lack tRNA introns; and/or (ii) they are not known to have an enzymatic pathway that generates 2'-PO4, 3'-5' phosphodiester RNA structures. There are more evidence showing that Tpt1 homologues are not limited to the canonical activity of Tpt1 healing the 2'-PO4, 3'-5' phosphodiester RNA splice junction formed during fungal and plant tRNA splicing [PUBMED:31019096]. Instead, the ADP-ribosyl transfer to a phosphorylated substrate is the unifying mechanistic feature of Tpt1-catalyzed reactions. For instance, some Tpt1 homologues have been shown to catalyze the transfer of ADP-ribose from NAD+ to a 5'-monophosphate end of RNA or DNA to install a 5'-phospho-ADP-ribose cap structure [PUBMED:30202863].

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Source: Pfam 34.0, rp75 Number of sequences: 2168 Average length of the domain: 171 aa HMM: Model length: 231 Clustering level: 80% Alignment: ClustalO Additional information: sequences longer than 50 amino acids