Inhibition of rat kidney mitochondrial DNA, RNA and protein synthesis by halogenated cysteine S-conjugates

Abstract

The effect of S-(1,2,3,4,4-pentachloro-1,3-butadienyl)-L-cysteine (PCBC), a metabolite of the nephrocarcinogen hexachloro-1,3-butadiene, and related cysteine S-conjugates on rat kidney mitochondrial DNA, RNA and protein synthesis was studied. Chloramphenicol-sensitive mitochondrial protein synthesis was inhibited (greater than 95%) by 0.5 mM PCBC. Similarly, mtRNA synthesis was inhibited (approximately 80%) by 0.125 mM PCBC, and mtDNA synthesis was inhibited by 0.125-0.5 mM PCBC. The cysteine S-conjugates S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine and S-(1,2-dichlorovinyl)-L-cysteine were less potent inhibitors. The effects of PCBC on DNA, RNA and protein synthesis were blocked by aminooxyacetic acid, an inhibitor of cysteine conjugate beta-lyase, thus demonstrating the essential role of beta-lyase in the bioactivation of PCBC. In mitochondria incubated with PCBC for 1 h, 60% of the high mol. wt DNA was degraded. Agarose gel electrophoresis of mtDNA showed that the supercoiled form was converted to the relaxed circular form and to shorter linear fragments. These studies show that PCBC, a metabolite of the nephrocarcinogen hexachloro-1,3-butadiene, has important effects on mitochondrial macromolecule synthesis and on the mitochondrial genome.