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. Author manuscript; available in PMC: 2016 Jul 3.
Published in final edited form as: J Mol Biol. 2015 Apr 19;427(13):2305–2318. doi: 10.1016/j.jmb.2015.04.006

Figure 6.

Figure 6

Gyrase relaxes DAP DNA more slowly. (a) Three offset, representative records of gyrase-catalyzed relaxations of normal (left) and DAP DNA (right) under 0.6 pN tension and with 1 mM ATP. The raw data (dots) and 0.5 s moving averages (solid lines) show variable delays before processive relaxation of supercoils that restored the tether to an extended state. Occasional pauses in the processive increases of tether length are evident (circled interval). (b) By ignoring pauses and converting tether length changes to twist of DNA, gyrase was found to more slowly relax DAP (crosses) than normal DNA (open circles) at several ATP concentrations. Fits of a Michaelis-Menten model are shown for normal (solid, Km = 0.16 mM, Vmax = 2.9 turns/s) and DAP (dashed, Km = 0.12 mM, Vmax = 1.93 turns/s) DNA. (c) Average pauses during otherwise processive relaxation were similar for gyrase acting on both types of DNA at all ATP concentrations (see also Figure S3).