Dihydrouridine

Dihydrouridine (abbreviated as D,[1] DHU, or UH2) is a pyrimidine nucleoside which is the result of adding two hydrogen atoms to a uridine, making it a fully saturated pyrimidine ring with no remaining double bonds. D is found in tRNA and rRNA molecules as a nucleoside; the corresponding nucleobase is 5,6-dihydrouracil.

Structure of base pair Adenine Dihydrouracil (AD)
Dihydrouridine
Names
IUPAC name
1-[(2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]-1,3-diazinane-2,4-dione
Other names
5,6-dihydrouridine
1,3,5,6-tetrahydrouridine
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.257.727
UNII
Properties
C9H14N2O6
Molar mass 246.217 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Because it is non-planar, D disturbs the stacking interactions in helices and destabilizes the RNA structure. D also stabilizes the C2’-endo sugar conformation, which is more flexible than the C3’-endo conformation; this effect is propagated to the 5’-neighboring residue. Thus, while pseudouridine and 2’-O-methylations stabilize the local RNA structure, D does the opposite.[2]

The tRNAs of organisms that grow at low temperatures (psychrophiles) have high 5,6-dihydrouridine levels (40-70% more on average) which provides the necessary local flexibility of the tRNA at or below the freezing point.[3]

References

  1. IUPAC-IUB Commission on Biochemical Nomenclature (1970). "Abbreviations and symbols for nucleic acids, polynucleotides, and their constituents". Biochemistry. 9 (20): 4022–4027. doi:10.1021/bi00822a023.
  2. Dalluge JJ; Hashizume T; Sopchik AE; McCloskey JA; Davis DR. (Mar 15, 1996). "Conformational flexibility in RNA: the role of dihydrouridine". Nucleic Acids Res. 24 (6): 1073–1079. doi:10.1093/nar/24.6.1073. PMC 145759. PMID 8604341.
  3. Dalluge JJ; Hamamoto T; Horikoshi K; Morita RY; Stetter KO; McCloskey JA (March 1, 1997). "Posttranscriptional modification of tRNA in psychrophilic bacteria". J Bacteriol. 179 (6): 1918–1923. PMC 178914. PMID 9068636.
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