Journal
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Volume 624, Issue -, Pages 146-150Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bbrc.2022.07.104
Keywords
Qtr3; SPAC589.05c; ribonucleoside hydrolase; ribonucleoside glycosylase; urh1; urh2
Categories
Funding
- Deutsche Forschungsgemeinschaft [SPP1784, EH237/13e1, EH237/13e2, GRK2338, SFB1032]
- DAAD (Deutscher Akademischer Austauschdienst)
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Queuosine (Q) is a nucleoside that plays a crucial role in faithful translation of codons in tRNAs. While bacteria can synthesize Q de novo, eukaryotes rely on external sources for Q modification. This study identified Qng1 as a queuosine nucleoside glycosylase in Schizosaccharomyces pombe, which is responsible for salvaging Q from bacterial sources and recycling Q from endogenous tRNAs.
Queuosine (Q) is a hypermodified 7-deaza-guanosine nucleoside that is found at position 34, also known as the wobble position, of tRNAs with a GUN anticodon, and Q ensures faithful translation of the respective C- and U-ending codons. While Q is present in tRNAs in most eukaryotes, only bacteria can synthesize it de novo. In contrast, eukaryotes rely on external sources like their food and the gut microbiome in order to Q-modify their tRNAs, and Q therefore can be regarded as a micronutrient. The eukaryotic tRNA guanine transglycosylase (eTGT) uses the base queuine (q) as a substrate to replace G34 by Q in the tRNAs. Eukaryotic cells can uptake both q and Q, raising the question how the Q nucleoside is converted to q for incorporation into the tRNAs. Here, we identified Qng1 (also termed Duf2419) as a queuosine nucleoside glycosylase in Schizosaccharomyces pombe. S. pombe cells with a deletion of qng1(+) contained Q-modified tRNAs only when cultured in the presence of the nucleobase q, but not with the nucleoside Q, indicating that the cells are proficient at q incorporation, but not in Q hydrolysis. Furthermore, purified recombinant Qng1 hydrolyzed Q to q in vitro. Qng1 displays homology to DNA glycosylases and has orthologs across eukaryotes, including flies, mice and humans. Qng1 therefore plays an essential role in allowing eukaryotic cells to salvage Q from bacterial sources and to recycle Q from endogenous tRNAs. (c) 2022 Elsevier Inc. All rights reserved.
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