DNA Helicases: Chemistry and Mechanisms

Abstract

DNA helicases are members of a larger class of enzymes composed of molecular motors that couple the energy of NTP binding and hydrolysis to directional translocation along a nucleic acid lattice. Structurally and mechanistically related helicases perform drastically different roles in DNA metabolism by associating with various macromolecular machineries that orchestrate DNA processing events. Within these macromolecular ensembles, DNA helicase translocation is coupled to separation of duplex DNA into two single strands, which is necessary for DNA replication, repair, recombination and transcription. Translocation by DNA helicases can also result in the disassembly of protein–nucleic acid complexes formed during DNA metabolism. One major consequence of cellular dependence on DNA helicases is that defects in these enzymes result in a broad spectrum of disorders usually characterized by premature aging, susceptibility to cancer, and other diseases normally associated with aging.