Dihydrouridine
Dihydrouridine (D) is a pyrimidine 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.
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 then the C3’-endo conformation, and 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. [1]
tRNA 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.[2]
References
- ^
Dalluge JJ (1996). "Conformational flexibility in RNA: the role of dihydrouridine". Nucleic Acids Res. 24(6): 1073–9. PMID 8604341. {{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ Dalluge JJ (1997). "Posttranscriptional modification of tRNA in psychrophilic bacteria". J Bacteriol. 179(6): 1918–23. PMID 9068636.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help)
