Loss of Coding Properties of the Oligonucleotide Adenylyluridylylguanosine after Photoreduction or Hydration

Abstract

The 5, 6-dihydrouridylic acid in s RNA may be a component of other types of RNA. Dihydropyrimidine dehydrogenases reversibly interconvert uridylic and dihydrouridylic acid indicating that dihydrouridylic acid may participate in protein synthesis. The presence of 1 or more dihydrouridylic acid residues in a viral messenger RNA together with the existence in the virus-infected cell of a nucleotide-sequence-specific dihydrouridine dehydrogenase might constitute a translational control mechanism for viral protein synthesis. This interconversion of uridylic acid and dihydrouridylic acid in messenger RNA may have a functional effect because the properties of uridylic acid are considerably altered when the 5, 6-double bond is saturated to give either dihydrouridylic acid or the closely similar 5-hydro-6-hydroxyuridylic acid. Dihydrouridylic acid residues in poly (U, H2U) copolymers are unable to form a helical structure with poly A. The partial conversion of uridine into dihydrouridine or 5-hydro-6-hyd-roxyuridine in poly U decreased the incorporation of phenylaline. Though the trinucleoside diphosphate GpUpU was unable to bind valyl-s-RNA if any or both of the uridine residues were replaced by dihydrouridine, the binding of phenylalanyl-s RNA may not be sensitive to the amount of dihydrouridylic acid in copolymers of uridylic acid and dihydrouridylic acid.