QTRT1
Function
Catalytic subunit of the queuine tRNA-ribosyltransferase (TGT) that catalyzes the base-exchange of a guanine (G) residue with queuine (Q) at position 34 (anticodon wobble position) in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr), resulting in the hypermodified nucleoside queuosine (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine) (PubMed:11255023, PubMed:20354154, PubMed:34009357, PubMed:34241577). Catalysis occurs through a double-displacement mechanism. The nucleophile active site attacks the C1' of nucleotide 34 to detach the guanine base from the RNA, forming a covalent enzyme-RNA intermediate. The proton acceptor active site deprotonates the incoming queuine, allowing a nucleophilic attack on the C1' of the ribose to form the product (By similarity). Modification of cytoplasmic tRNAs with queuosine controls the elongation speed of cognate codons, thereby ensuring the correct folding of nascent proteins to maintain proteome integrity (PubMed:30093495).
Sequence Similarities
Belongs to the queuine tRNA-ribosyltransferase family.
Cellular localization
- Cytoplasm
- Mitochondrion outer membrane
- Peripheral membrane protein
- Cytoplasmic side
- Weakly associates with mitochondria, possibly via QTRT2.
Alternative names
TGT, TGUT, QTRT1, Queuine tRNA-ribosyltransferase catalytic subunit 1, Guanine insertion enzyme, tRNA-guanine transglycosylase