Control of DNA polymerase gp5 chain substitution by DNA double strand annealing pressure

DNA polymerase is essential for replication and repair. As it only performs the 5?-3? polymerization, there are two kinds of replication. One them called strand-displacement synthesis: opens double-strand (ds) to attain 3?-5?strand (leading strand) copy this template in a continuous way, other extension copies newly separated strand (lagging discontinuous manner. The complex T7 phage an optimal model investigate mechanism because constituted by 4 terms protein which helicase gp4, gp5 with co-factor thioredoxin (Trx), single-strand (ss) DNA-binding gp2.5. encounters both synthesis synthesis. Previous researches reported that can have rapid but lacks ability It also gp4 translocates on ssDNA at speed unwinds dsDNA very low speed. However, together processive Although extensively studied, remains unclear. Here work, dynamic investigated single-molecule Förster (fluorescence) resonance energy transfer (smFRET). found gp5, without help external tension, open about base pairs (bp), its exonuclease activity excises nascent nucleotides. Therefore repeats synthesis-excision cycle results less production We conduct another control experiment nano-tensioner, high precision smFRET setup exert tension dsDNA, change regression pressure gp5. observed reduced increase length reduce excision indicates regulate further shows after assembled into replisome, barely any presented. replisome little higher than alone much alone. Additionally, longer indicated enables On hand, facilitates unwind dsDNA.