uracil glycol (Ug)

FULL NAME: 5,6-dihydroxy-5,6-dihydrouracil


DESCRIPTION:
A major stable oxidation product of DNA cytosine is 5,6-dihydroxy-5,6-dihydrouracil (Ug). Ug can be formed directly in DNA or in the cellular nucleotide pools by deamination of the unstable primary product, cytosine glycol. Ug is a strong premutagenic lesion, blocking DNA polymerase. Products of cytosine may deaminate and dehydrate. Cytosine glycol deaminates to give uracil glycol, 5-hydroxycytosine, and 5-hydroxyuracil. However, cytosine glycol, uracil glycol, 5-hydroxycytosine, and 5-hydroxyuracil were all detected in γ-irradiated cytosine, indicating that all these compounds may simultaneously be present in damaged DNA. In the absence of oxygen, C5-OH adduct radicals may be reduced, followed by protonation to give 5-hydroxy-6-hydropyrimidines. 5-Hydroxy-6-hydrocytosine readily deaminates into 5-hydroxy-6-hydrouracil. Similarly, C6-OH adduct radicals of pyrimidines may lead to 6-hydroxy-5-hydropyrimidines. These products are typical of anoxic conditions because oxygen inhibits their formation by reacting with OH adduct radicals.

DAMAGE TYPE: hydrate


DNA DAMAGE SOURCE(S) (MAIN):
reactive oxygen species (ROS)
ionizing radiation (IR)


DNA DAMAGE SOURCE(S) (MINOR):
spontaneous deamination


DNA DAMAGE EFFECT(S) (MAIN):
mutagenesis
stalled replication fork


DNA DAMAGE EFFECT(S) (MINOR):
mutagenesis
substitution


PATHWAYS:
base excision repair (BER)


DNA repair protein(s) related to damage:
Nth (endo III)
Fpg (MutM)
Nth (endo III)
Nei (endo VIII)


Last modification date: Oct. 9, 2011