||Bacteria Escherichia coli
||Sekiya M, Nakamoto RK, Al-Shawi MK, Nakanishi-Matsui M, Futai M. Temperature dependence of single molecule rotation of the Escherichia coli ATP synthase F1 sector reveals the importance of gamma-beta subunit interactions in the catalytic dwell. J Biol Chem. 2009 Aug 14 284(33):22401-10PubMed ID19502237
||The temperature-dependent rotation of F1-ATPase gamma subunit was observed in V(max) conditions at low viscous drag using a 60-nm gold bead. Using a data collection rate of 4,000–8,000 frames/s allowed researchers to detect the intervening short pauses between 120° rotation steps during continuous rotation behavior. Researchers previously concluded that ATP hydrolysis occurs during the short pause and is thus called the catalytic dwell (21). This dwell corresponds to the pause between the 80° and 40° substeps as observed by Yasuda et al. (19).
||The duration of the catalytic dwell became slightly shorter with increasing temperature for example, the average dwell lengths at 17 and 31 °C were 0.22 ± 0.014 and 0.15 ± 0.016 ms, respectively. Researchers find that there is dramatic effect of the mutation ?M23K compared to wildtype on the temperature dependence of the length of the catalytic dwell or pause between the 120° rotation steps. This is likely because of two factors: first, they used a bead small enough not to invoke a drag on the rotation (32), and second, the temperature dependence of the rate of the rotation steps is critical for the analyses of the mechanism.