Queuosine salvage in fission yeast by Qng1-mediated hydrolysis to queuine.
Biochem Biophys Res Commun
; 624: 146-150, 2022 10 08.
Article
em En
| MEDLINE
| ID: mdl-35940128
ABSTRACT
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 denovo. 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.
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MEDLINE
Assunto principal:
Schizosaccharomyces
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Nucleosídeo Q
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article