Queuine

Queuine

Queuine is a naturally occurring modified nucleoside found in the RNA of many eukaryotes, including animals, plants, and fungi, as well as in some bacteria. It is a member of the guanine family and is notable for its role in the modification of the nucleotide guanosine in the tRNA molecule. Queuine is incorporated into tRNA through a post-transcriptional modification process, replacing the guanine at the wobble position of certain tRNAs. This modification is crucial for the proper decoding of the genetic code and for the maintenance of protein synthesis fidelity.

The biosynthesis of queuine is complex and involves several enzymatic steps. In bacteria, queuine is synthesized de novo, whereas eukaryotes and some other organisms must obtain it through their diet or from their gut microbiota, as they lack the pathways for its de novo synthesis. This dependency underscores the importance of queuine in biological systems and suggests a symbiotic relationship between hosts and their microbiota regarding queuine metabolism.

The presence of queuine in tRNA is essential for the structural stability of the tRNA molecule and for the efficiency and accuracy of protein synthesis. It has been shown to influence the folding and base-pairing properties of tRNA, affecting the codon-anticodon interaction and thereby influencing the translation process. Research has indicated that queuine may have a role in modulating the gene expression, cell differentiation, and response to oxidative stress, highlighting its potential involvement in various physiological and pathological processes.

Deficiencies in queuine or disruptions in its metabolism have been associated with various health issues, including cancer, neurological disorders, and infectious diseases. The study of queuine and its impact on health and disease is an ongoing area of research, with potential implications for the development of therapeutic strategies targeting queuine-related metabolic pathways.