Release of 3-methyladenine from nucleosomal DNA by a 3-methyladenine DNA glycosylase

Journal Article · Sat Jan 01 04:00:00 EST 1983 · Carcinogenesis (N.Y.); (United States)

DOI:https://doi.org/10.1093/carcin/4.2.145· OSTI ID:5779408

Price, J A; Heller, E; Goldthwait, D A

Nucleosomes from chicken erythrocytes, with DNA containing an average of 144 base pairs, were alkylated with (/sup 3/H)methylnitrosourea. The level of alkylation of the nucleosomal DNA was 48% of that of free DNA. The histones had approximately one tenth the radioactivity of the DNA. There was no statistically significant difference between alkylation of nucleosome bases in the major vs. minor groove. When the first 50 residues of the alkylated nucleosomal DNA were examined on sequencing gels, the 7-methylguanine and 3-methyladenine (3-MeA) residues were distributed randomly. The 3-MeA DNA glycosylase I of E. coli was used to measure the release of 3-MeA groups of the nucleosomal DNA. A partially purified 3-MeA DNA glycosylase from rat liver gave similar results. The limited enzymatic release is most likely due to steric hindrance of the enzyme by the DNA-Histone interactions on the surface of the core particle. An alteration of nucleosomal conformation has been suggested as an explanation for repair of nucleosomal DNA. Two model systems have been examined. The addition of ethidium bromide to alkylated nucleosomes increased the enzymatic release of 3-MeA to approx.75% and altered the electron microscopic appearance. The chemical alkylation of nucleosomes also increased the enzymatic release of 3-MeA as well as decreased the sedimentation coefficient. All of these experiments indicate a limited availability of 3-MeA residues to the glycosylase and suggest that some conformational change must occur in vivo for complete repair. 52 references, 6 figures, 4 tables.

• Research Organization: Case Western Reserve Univ., Cleveland, OH
• DOE Contract Number: AC02-76EV02725
• OSTI ID: 5779408
• Journal Information: Carcinogenesis (N.Y.); (United States), Journal Name: Carcinogenesis (N.Y.); (United States) Vol. 4:2; ISSN CRNGD
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADENINES
ALKYLATION
AMINES
ANIMALS
ANTIMETABOLITES
AROMATICS
AZAARENES
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BIRDS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CHEMICAL REACTIONS
CHICKENS
CHROMATIN
CONFORMATIONAL CHANGES
DATA
DIGESTIVE SYSTEM
DNA
DNA REPAIR
DNA-ASE
DRUGS
ENDONUCLEASES
ENZYME ACTIVITY
ENZYMES
ERYTHROCYTES
ESCHERICHIA COLI
ESTERASES
EXPERIMENTAL DATA
FOWL
GLANDS
HETEROCYCLIC COMPOUNDS
HISTONES
HYDROLASES
INFORMATION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIVER
MAMMALS
MATERIALS
MICROORGANISMS
MOLECULAR STRUCTURE
NITROSO COMPOUNDS
NITROSOUREAS
NUCLEIC ACIDS
NUCLEOSOMES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOSPHODIESTERASES
PROTEINS
PURINES
RATS
REACTION KINETICS
RECOVERY
REMOVAL
REPAIR
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES