Queuosine is a modified
nucleoside that is present in certain
tRNAs in
bacteria and
eukaryotes
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
. It contains the
nucleobase queuine
Queuine () (Q) is a hypermodified nucleobase found in the first (or wobble) position of the anticodon of tRNAs specific for Asn, Asp, His, and Tyr, in most eukaryotes and prokaryotes. Because it is utilized by all eukaryotes but produced exclusiv ...
. Originally identified in ''
E. coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'', queuosine was found to occupy the first anticodon position of tRNAs for
histidine,
aspartic acid
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
,
asparagine and
tyrosine. The first anticodon position pairs with the third "
wobble" position in codons, and queuosine improves accuracy of
translation compared to
guanosine. Synthesis of queuosine begins with
GTP. In bacteria, three structurally unrelated classes of
riboswitch are known to regulate
genes that are involved in the synthesis or transport of pre-queuosine
1, a precursor to queuosine:
PreQ1-I riboswitches,
PreQ1-II riboswitch
PreQ1-II riboswitches form a class of riboswitches that specifically bind pre-queuosine1 (PreQ1), a precursor of the modified nucleoside queuosine. They are found in certain species of ''Streptococcus'' and ''Lactococcus'', and were originally i ...
es and
PreQ1-III riboswitch
PreQ1-III riboswitches are a class of riboswitches that bind pre-queuosine1 (PreQ1), a precursor to the modified nucleoside queuosine.
PreQ1-III riboswitches are the third class of riboswitches to be discovered that sense this ligand, and are struc ...
es.
Queuosine biosynthesis genes have also been found on phage genomes and may be involved in protection from genome degradation by the host.
References
External links
* Wikigenes
Queuosine* Human Metabolome Database
Queuosine (HMDB11596)* {{cite journal , doi = 10.1002/anie.200604579, pmid = 17310487, title = Synthesis of the Transfer-RNA Nucleoside Queuosine by Using a Chiral Allyl Azide Intermediate, journal = Angewandte Chemie International Edition, volume = 46, issue = 13, pages = 2325–2327, year = 2007, last1 = Klepper, first1 = Florian, last2 = Jahn, first2 = Eva-Maria, last3 = Hickmann, first3 = Volker, last4 = Carell, first4 = Thomas
Nucleosides
Pyrrolopyrimidines
Tetrahydrofurans
Cyclopentenes
Hydroxymethyl compounds