cytosine glycol (Cg)

FULL NAME: 4-amino-5,6-dihydroxy-5,6-dihydropyrimidin-2(1H)-one


DESCRIPTION:
Cytosine glycol (5,6-dihydroxy-5,6-dihydrocytosine) is initial products of cytosine oxidation. Cg is not stable. Oxidation of cytosine involves saturation of the 5,6-double bond of cytosine, rendering the exocyclic amino group susceptible to deamination, i.e. conversion of the amino to a carbonyl group. Because these groups dictate base pairing in duplex DNA, both thermally and oxidatively induced deamination are efficient mechanisms of GC→AT transition mutations. The majority of studies on cytosine oxidation has focused on three modifications: uracil glycols, 5-hydroxycytosine and 5-hydroxyuracil. These modifications are believed to arise from intermediate cytosine glycols, which undergo deamination to uracil glycols, dehydration to 5-hydroxycytosine, or both deamination and dehydration to 5-hydroxyuracil. These modifications are substrates for numerous DNA repair proteins, including Nth homologues (Endo III, hNTH1), Nei-like homologues (Endo VIII, yNtg1/yNtg2, hNeil1/hNeil2), uracil N-glycosylases (Ung and Smug1) and Nfo-like endonucleases with nucleotide incision activity (Apn1, Ape1).

DAMAGE TYPE: hydrate


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


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


DNA DAMAGE EFFECT(S) (MAIN):
C→T transition
transition


PATHWAYS:
base excision repair (BER)


DNA repair protein(s) related to damage:
NTHL1


Last modification date: Oct. 9, 2011