Queuosine is a modified nucleoside

Nucleoside

Nucleosides are glycosylamines consisting of a nucleobase bound to a ribose or deoxyribose sugar via a beta-glycosidic linkage...

 that is present in certain tRNAs in bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 and eukaryotes. Originally identified in E. coli

Escherichia coli

Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

, queuosine was found to occupy the first anticodon position of tRNAs for histidine

Histidine

Histidine Histidine, an essential amino acid, has a positively charged imidazole functional group. It is one of the 22 proteinogenic amino acids. Its codons are CAU and CAC. Histidine was first isolated by German physician Albrecht Kossel in 1896. Histidine is an essential amino acid in humans...

, aspartic acid

Aspartic acid

Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...

, asparagine

Asparagine

Asparagine is one of the 20 most common natural amino acids on Earth. It has carboxamide as the side-chain's functional group. It is not an essential amino acid...

 and tyrosine

Tyrosine

Tyrosine or 4-hydroxyphenylalanine, is one of the 22 amino acids that are used by cells to synthesize proteins. Its codons are UAC and UAU. It is a non-essential amino acid with a polar side group...

. The first anticodon position pairs with the third "wobble

Wobble base pair

In molecular biology, a wobble base pair is a non-Watson-Crick base pairing between two nucleotides in RNA molecules. The four main wobble base pairs are guanine-uracil, inosine-uracil, inosine-adenine, and inosine-cytosine . The thermodynamic stability of a wobble base pair is comparable to that...

" position in codons, and queuosine improves accuracy of translation

Translation

Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. Whereas interpreting undoubtedly antedates writing, translation began only after the appearance of written literature; there exist partial translations of the Sumerian Epic of...

. Synthesis of queuosine begins with GTP

Guanosine triphosphate

Guanosine-5'-triphosphate is a purine nucleoside triphosphate. It can act as a substrate for the synthesis of RNA during the transcription process...

. In bacteria, two classes of riboswitch

Riboswitch

In molecular biology, a riboswitch is a part of an mRNA molecule that can directly bind a small target molecule, and whose binding of the target affects the gene's activity. Thus, an mRNA that contains a riboswitch is directly involved in regulating its own activity, in response to the...

 are known to regulate gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s that are involved in the synthesis or transport of pre-queuosine₁, a precursor to queuosine: PreQ1-I riboswitch

PreQ1 riboswitch

The PreQ1-I riboswitch is a cis-acting element identified in bacteria which regulates expression of genes involved in biosynthesis of the nucleoside queuosine from GTP. This RNA element known as a riboswitch binds preQ1 , an intemediate in the queuosine pathway...

es and PreQ1-II riboswitch

PreQ1-II riboswitch

PreQ1-II riboswitches form a class of riboswitches that specifically bind pre-queosine1 , a precursor of the modified nucleoside queuosine. They are found in certain species of Streptococcus and Lactococcus, and were originally identified as a conserved RNA secondary structure called the "COG4708...

es.

Literature

• Florian Klepper: Synthese der natürlichen tRNA Nukleosidmodifikationen Queuosin und Archaeosin, Dissertation, München 2007.
• Florian Klepper, Eva-Maria Jahn, Volker Hickmann, Thomas Carell
  Thomas Carell
  Thomas Carell is a German biochemist.Carell was born in 1966 in Herford Germany, he studied chemistry from 1985 till 1990 at the University of Münster finishing with a diploma thesis at the Max Planck Institute for Medical Research Heidelberg. After his PhD thesis on Porphyrin chemistry at the same...
  
  : „Synthese des tRNA-Nucleosids Queuosin unter Verwendung eines chiralen Allylazid-Intermediats“, Angewandte Chemie
  Angewandte Chemie
  Angewandte Chemie is a weekly peer-reviewed scientific journal that covers all aspects of chemistry. Its impact factor was 12.730 in 2010, the highest value for a chemistry-specific journal that publishes original research...
  
  , 2007, 119 (13), pp. 2377–2379; .
• Florian Klepper, Eva-Maria Jahn, Volker Hickmann, Thomas Carell
  Thomas Carell
  Thomas Carell is a German biochemist.Carell was born in 1966 in Herford Germany, he studied chemistry from 1985 till 1990 at the University of Münster finishing with a diploma thesis at the Max Planck Institute for Medical Research Heidelberg. After his PhD thesis on Porphyrin chemistry at the same...
  
  : „Synthesis of the Transfer-RNA Nucleoside Queuosine by Using a Chiral Allyl Azide Intermediate“, Angewandte Chemie International Edition, 2007, 46 (13), pp. 2325–2327; .

External Links

• Wikigenes: Queuosine
• Human Metabolome Database: Queuosine (HMDB11596)