UV-induced pyrimidine hydrates in DNA are required by bacterial and mammalian DNA glycosylase activities

Journal Article · Tue Jul 25 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00441a007· OSTI ID:5353437

Boorstein, R J; Hilbert, T P; Cadet, J; Cunningham, R P; Teebor, G W ^[1]

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1. New York Univ. Medical Center, New York (USA)

Escherichia coli endonuclease III and mammalian repair enzymes cleave UV-irradiated DNA at AP sites formed by the removal of cytosine photoproducts by the DNA glycosylase activity of these enzymes. Poly(dG-({sup 3}H)dC) was UV irradiated and incubated with purified endonuclease III. {sup 3}H-Containing material was released in a fashion consistent with Michaelis-Menten kinetics. This {sup 3}H material was determined to be cytosine by chromatography in two independent systems and microderivatization. {sup 3}H-Containing material was not released from nonirrdiated copolymer. When poly(dA-({sup 3}H)dU) was UV irradiated, endonuclease III released {sup 3}H-containing material that coeluted with uracil hydrate (6-hydroxy-5,6-dihydrouracil). Similar results are obtained by using extracts of HeLa cells. There results indicate that the modified cytosine residue recognized by endonuclease III and the mammalian enzyme is cytosine hydrate (6-hydroxy-5,6-dihydrocytosine). Once released from DNA through DNA-glycosylase action, the compound eliminates water, reverting to cytosine. This is consistent with the known instability of cytosine hydrate. The repairability of cytosine hydrate in DNA suggests that it is stable in DNA and potentially genotoxic.

• OSTI ID: 5353437
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:15; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
AZINES
BACTERIA
BARYONS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CARBON 14 COMPOUNDS
CYTOSINE
DNA REPAIR
DNA-ASE
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENDONUCLEASES
ENZYME ACTIVITY
ENZYMES
ESCHERICHIA COLI
ESTERASES
FERMIONS
GLYCOSYL HYDROLASES
HADRONS
HELA CELLS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
KINETICS
LABELLED COMPOUNDS
MICROORGANISMS
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOSPHODIESTERASES
PROTONS
PYRIMIDINE DIMERS
PYRIMIDINES
RADIATIONS
RADIOINDUCTION
REACTION KINETICS
RECOVERY
REPAIR
THYMINE
TRITIUM COMPOUNDS
ULTRAVIOLET RADIATION
URACILS