Interstrand and Intrastrand DNA−DNA Cross-Linking by 1,2,3,4-Diepoxybutane:  Role of Stereochemistry

Abstract

1,2,3,4-Diepoxybutane (DEB) is a bifunctional electrophile capable of forming DNA-DNA and DNA-protein cross-links. DNA alkylation by DEB produces N7-(2'-hydroxy-3',4'-epoxybut-1'-yl)-guanine monoadducts, which can then form 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) lesions. All three optical isomers of DEB are produced metabolically from 1,3-butadiene, but S,S-DEB is the most cytotoxic and genotoxic. In the present work, interstrand and intrastrand DNA-DNA cross-linking by individual DEB stereoisomers was investigated by PAGE, mass spectrometry, and stable isotope labeling. S,S-, R,R-, and meso-diepoxides were synthesized from l-dimethyl-2,3-O-isopropylidene-tartrate, d-dimethyl-2,3-O-isopropylidene-tartrate, and meso-erythritol, respectively. Total numbers of bis-N7G-BD lesions (intrastrand and interstrand) in calf thymus DNA treated separately with S,S-, R,R-, or meso-DEB (0.01-0.5 mM) were similar as determined by capillary HPLC-ESI(+)-MS/MS of DNA hydrolysates. However, denaturing PAGE has revealed that S,S-DEB produced the highest number of interchain cross-links in 5'-GGC-3'/3'-CCG-5' sequences. Intrastrand adduct formation by DEB was investigated by a novel methodology based on stable isotope labeling HPLC-ESI(+)-MS/MS. Meso DEB treatment of DNA duplexes containing 5'-[1,7, NH(2)-(15)N(3),2-(13)C-G]GC-3'/3'-CCG-5' and 5'-GGC-3'/3'-CC[(15)N(3),2-(13)C-G]-5' trinucleotides gave rise to comparable numbers of 1,2-intrastrand and 1,3-interstrand bis-N7G-BD cross-links, while S,S DEB produced few intrastrand lesions. R,R-DEB treated DNA contained mostly 1,3-interstrand bis-N7G-BD, along with smaller amounts of 1,2-interstrand and 1,2-intrastrand adducts. The effects of DEB stereochemistry on its ability to form DNA-DNA cross-links may be rationalized by the spatial relationships between the epoxy alcohol side chains in stereoisomeric N7-(2'-hydroxy-3',4'-epoxybut-1'-yl)-guanine adducts and their DNA environment. Different cross-linking specificities of DEB stereoisomers provide a likely structural basis for their distinct biological activities.

DNA Interstrand Cross-Linking by Epichlorohydrin

“…A previous report used mass spectrometry to confirm interstrand cross-linking of this duplex by DEB (39). As also observed by Tretyakova and co-workers (39), multiple bands of mobility lower than that of single strands were visible upon denaturing gel electrophoresis of this cross-linked duplex ( Figure 5).…”

“…Centrally cross-linked DNA has the lowest mobility on denaturing gels (40); therefore, we expected that the highest band corresponded to cross-linking at the 5′-GGC site. Tretyakova and co-workers also assigned this lowest-mobility band as the centrally crosslinked duplex (39). We independently confirmed this assignment through purification and piperidine cleavage.…”

Structure of the 1,4-Bis(2‘-deoxyadenosin-N6-yl)-2S,3S-butanediol Intrastrand DNA Cross-Link Arising from Butadiene Diepoxide in the Human N-ras Codon 61 Sequence

“…Park et al (56) proposed a model in which the differences between the ability of different BDO 2 stereoisomers to induce N7,N7-dG cross-links might be caused by different orientations of functional groups in stereoisomeric N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)-guanine intermediates. Thus, for S,S-and R,R-N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)-guanine, the oxirane and the 2′-hydroxy group reside on one side of the plane formed by the carbon chain, while, in the cross-link arising from the meso BDO 2 , the oxirane and the 2′-OH are on different sides of the plane, potentially influencing the site of the second alkylation.…”

“…The formation of N7,N7-dG cross-links is dependent upon stereochemistry of the BDO 2 ; with S,S BDO 2 > R,R BDO 2 > meso BDO 2 (56,57). Treatment of DNA with meso BDO 2 yields comparable numbers of 1,2-intra-strand and 1,3-inter-strand bis-N7-dG cross-links, while S,S BDO 2 produces few intra-strand cross-links.…”

DNA repair decline during mouse spermiogenesis results in the accumulation of heritable DNA damage

“…BD is metabolized by the cytochrome P-450-dependent monoxygenases to 1,2-epoxybutene-3 (EB), which is further metabolized by oxidation to diepoxybutane (DEB) [39][40][41]. DEB is a bifunctional alkylating agent that induces interstrand and intrastrand DNA-DNA crosslinks by alkylating two adjacent bases within the major grove of a DNA duplex [42,43] and DNA-protein crosslinks [44][45][46]. DEB is both a somatic and germ cell mutagen in mammals [47][48][49].…”