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Title: INTERACTION OF BENZO(A)PYRENE DIOL EPOXIDE WITH SVAO MINICHROMOSOMES

Journal Article · · Nucleic Acid Research
OSTI ID:1068177
; ;

SV40 minichromosomes were reacted with (+)7{beta},8{alpha}-dihydroxy-9{alpha},10{alpha}-epoxy- 7,8,9,10-tetrahydrobenzo[a]pyrene (BaP diol epoxide). Low levels of modification (< 5 DNA adducts/minichromosome) did not detectably alter the structure of the minichromosomes but high levels (> 200 DNA adducts/minichromosome) led to extensive fragmentation. Relative to naked SV40 DNA BaP diol epoxide induced alkylation and strand scission of minichromosomal DNA was reduced or enhanced by factors of 1.5 and 2.0, respectively. The reduction in covalent binding was attributed to the presence of histones, which competed with DNA for the hydrocarbon and reduced the probability of BaP diol epoxide intercalation by tightening the helix. The enhancement of strand scission was probably due to the catalytic effect of histones on the rate of S-elimination at apurinic sites, although an altered adduct profile or the presence of a repair endonuclease were not excluded. Staphylococcal nuclease digestion indicated that BaP dial epoxide randomly alkylated the minichromosomal DNA. This is in contrast to studies with cellular chromatin where internucleosomal DNA was preferentially modified. Differences in the minichromosomal protein complement were responsible for this altered susceptibility.

Research Organization:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
Chemical Sciences Division
DOE Contract Number:
DE-AC02-05CH11231
OSTI ID:
1068177
Report Number(s):
LBL-10662
Journal Information:
Nucleic Acid Research, Journal Name: Nucleic Acid Research
Country of Publication:
United States
Language:
English

Figures / Tables (8)

Figure 1(p. 28)figure Figure 1
Figure 2(p. 29)figure Figure 2
Figure 3(p. 30)figure Figure 3
Figure 4(p. 31)figure Figure 4
Figure 5(p. 32)figure Figure 5
Figure 6(p. 33)figure Figure 6
32P]-chromatin was incubated 20 min at 37° with [3H]-BaP diol epoxide (molar reaction ratio = 0.55) in the gradient isolation buffer. The alkylated chromatin (0.74 DNA adducts/minichromosome) was immediately digested with 4.3 E.U. staphylococcal nuclease/μg viral DNA. Aliquots were taken over a 20 min period into EDTA. Ethanol precipitable radioactivity was determined after deproteinization and ethyl acetate extraction. (●), minichromosoma1 DNA; (○), BaP diol epoxide DNA adducts. 100% = 12,800 cpm 32P and 650 cpm 3H." data-ostiid="1068177">
Figure 7(p. 34)figure Figure 7
32P]chromatin .was incubated 20 min at 37° with [3H]-BaP diol epoxide (molar reaction ratio = 0.44) in 20 mM Tris-HCl, pH 8.0-0.5 mM EDTA-3% dimethyl sulfoxide. The alkylated chromatin (27.5 adducts/minichromosome) was immediately digested with 9.5 E.U. staphylococcal nuclease/pg viral DNA in the absence of NaC1. Aliquots were analyzed as outlined in Figure 7. (●), minichromosomal DNA; (○), BaP diol epoxide DNA adducts. 100% = 6,000 cpm 32P and 5,100 cpm 3H." data-ostiid="1068177">
Figure 8(p. 35)figure Figure 8

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