Insight into helicase mechanism and function revealed through single - molecule approaches

Helicases are a class of nucleic acid (NA) motors that catalyze NTP-dependentunwinding of NA duplexes into single strands, a reaction essential to all areas of NAmetabolism. In the last decade, single-molecule (sm) technology has proven to be highly usefulin revealing mechanistic insight into helicase activity that is not always detectable via ensembleassays. A combination of methods based on fluorescence, optical and magnetic tweezers, andflow-induced DNA stretching has enabled the study of helicase conformational dynamics, forcegeneration, step size, pausing, reversal and repetitive behaviors during translocation andunwinding by helicases working alone and as part of multiprotein complexes. The contributionsof these sm investigations to our understanding of helicase mechanism and function will be discussed