Homodinuclear (Pt,Pt) and heterodinuclear (Ru,Pt) metal compounds as DNA-protein cross-linking agents: Potential suicide DNA lesions

Abstract

Homodinuclear (Pt,Pt) and heterodinuclear (Ru,Pt) metal compounds having the generalized formula M(a)NH2(CH)4NH2M(b) are shown to form specific DNA lesions which can efficiently cross-link proteins to DNA. In this study, the homodinuclear case is represented by M(a) = M(b) = [cis-Pt(Cl2)-(NH3)] and the heterodinuclear case is represented by M(a) = [cis-RuCl2(DMSO)3] and M(b) = [cis-PtCl2(NH3)]. Native and denaturing polyacrylamide gel electrophoresis was used to show the formation of ternary coordination complexes between the metal-treated 49-bp DNA fragment and the Escherichia coli UvrA and UvrB DNA repair proteins. Treatment with proteinase K results in loss of the DNA-protein cross-links. DNA-protein cross-links formed between UvrA and DNA previously modified with the dinuclear metal compounds are reversible with the reducing agent beta-mercaptoethanol. The DNA lesion responsible for efficient DNA-protein cross-linking is most probably a DNA-DNA interstrand cross-link in which each metal atom is coordinated with one strand of the DNA helix. The formation of DNA repair protein associated DNA cross-links, potential "suicide adducts", suggests a novel action mechanism for these anticancer compounds. In addition, these dinuclear metal compounds should be very useful agents for the investigation of a wide range of protein-DNA interactions.

Structural and Functional Characterization of the Human DNA Repair Helicase XPD by Comparative Molecular Modeling and Site-directed Mutagenesis of the Bacterial Repair Protein UvrB

“…Reardon and Sancar (60) show that XPD is making intimate contact with a psoralen monoadduct. Similar studies have shown UvrB can also be cross-linked to psoralen (61)or bis-platinum adducts (62). This general approach, the development and validation of a structural model for other mammalian proteins, should be generally applicable where structural information exists for closely functional related bacterial, archaeal, or yeast proteins, which share significant protein structural motifs or a structural protein fold.…”

Incision of DNA–protein crosslinks by UvrABC nuclease suggests a potential repair pathway involving nucleotide excision repair

“…DPC levels increase dramatically upon exposure to a variety of physical or chemical agents, including UV light (4), ionizing radiation (5), ␤-propiolactone (6), aldehydes (1,(7)(8)(9), arsenite (10), ferric nitrilotriacetate (11), chromate (12), nickel (13), and others. Chemotherapeutic agents, such as cisplatin (12,14), bisplatinum (15), and neocarcinostatin (16), have also been shown to induce DPC formation. Exposure to several DPC-inducing agents gives rise to genotoxic and carcinogenic effects, and for some agents, such as formaldehyde, their primary mutagenic effects are believed to be mediated through the formation of DPCs (7,9).…”

DNA-Protein Cross-link Formation Mediated by Oxanine

“…Molecular weight markers were also electrophoresed side by side: phosphorylase (M r ϭ 97,400), albumin (66,267), aldolase (42,400), carbonic anhydrase (30,000), trypsin inhibitor (20,100), and lysozyme (14,400). The gel was briefly stained with Coomassie Brilliant Blue (CBB), dried, and subjected to autoradiography.…”

“…Although Oxa and 2-deoxyribonolactone are base and sugar lesions, respectively, they have a lactone structure in common that is prone to react with nucleophilic molecules. cis-Platinum, which is known to form DPC and is used as a anticancer drug, also induces cross-links between DNA and UvrA/UvrB proteins involved in nucleotide excision repair (66). Thus, irreversible inhibition of repair enzymes by covalent trapping has a dual biological effect: DPC formation in general and suicide of DNA repair enzymes in particular.…”