DNA electrochemistry of the E. coli helicase, DinG

Abstract

Coli helicase DinG, which can be induced by DNA damage, previously has been shown to have a [4Fe-4S] cluster. While the primary in vivo role of DinG has not been revealed, the protein has been implicated in clearing stalled replication forks that arise from the collision of oppositely oriented transcription and replication machinery. We have explored the DNA-bound redox potential of DinG using electrochem. on gold modified with a helicase substrate, a 20-mer oligonucleotide with a 15-mer overhang. The [4Fe-4S] cluster can be reduced and oxidized reversibly at a DNA-bound redn. potential of ∼ 80 mV vs. This DNA-mediated electrochem. signal, moreover, is stimulated by ATP-hydrolysis. Results from cellular activity assays suggest that DinG may cooperate with other DNA-processing enzymes that have [4Fe-4S] clusters to locate and process DNA damage products.