FeS-Induced Radical Formation and Its Effect on Plasmid DNA

Abstract

Plasmid DNA was incubated at 25°C with aqueous solutions of dissolved Fe(II), S(-II), and nanoparticulate FeS with a mackinawite structure, FeS m . At C0.1 mM total dissolved Fe(II) and S(-II), an increase in the proportion of the relaxed plasmid DNA occurs, through scission of the DNA backbone. In solutions where FeS m was precipitated, nanoparticulate FeS m binds to the DNA molecules. In solutions with concentrations below the FeS m solubility product, nicking of supercoiled pDNA occurs. Plasmid DNA appears to be a sensitive proxy for radical reactions. The reactant is proposed to be a sulfur-based radical produced from the iron-catalyzed decomposition of bisulfide, in a manner analogous to the Fenton reaction. This is further supported by experiments that suggest that sulfide free radicals are produced during the photolysis of aqueous solutions of polysulfides. Supercoiling of DNA affects nearly all DNA-protein transactions so the observation of relaxation of supercoiled forms through reaction with FeS solutions has direct implications to biochemistry. The results of this experimentation suggest that genotoxicity in FeS-rich systems is a further contributory factor to the limited survival of organisms in sulfidic environments. Mutations resulting from the interactions of organisms and mobile elements, such as plasmids, in sediments will also be affected in sulfide-rich environments.

Colloidal synthesis of biocompatible iron disulphide nanocrystals

“…In addition, supercoiled pDNA nicking occurs in solutions with concentrations below the FeSm solubility product. The authors proposed that plasmid DNA appears to be a sensitive proxy for radical reactions [37]. Interestingly, we showed that interaction between iron disulphide nanocrystals and mammalian cells does not affect cell viability.…”

Fe-catalyzed sulfide oxidation in hydrothermal plumes is a source of reactive oxygen species to the ocean

“…Subsequent reduction of the resulting Fe(III) by excess sulfide as the plume rose would have continued to produce H 2 O 2 and, at the measured pH range of the plume ( Table 1 ), the more reactive hydroxyl radical ( Eq. 3 ) ( 1 , 5 – 7 , 25 – 28 ).…”

Synthesis and application of iron sulfide−based materials to activate persulfates for wastewater remediation: a review

“…Bare Iron sulfide (FeS) nanoparticles were reported to bind with DNA, limiting the ability of DNA to interact with other nucleic acids and amino acids (Hatton and Rickard, 2008). Rickard, D. et al (Rickard, et al, 2011) proposed that when the concentration of FeS nanoparticles is lower than its solubility limit, it will cause incision in DNA molecules, and pose genotoxicity by reacting with polynucleic acids when above solubility limit. Furthermore, FeS particles will inhibit the growth of microorganisms and plants.…”