Measured parameters for the GTPase activity and polymerization of FtsZ from <i>Escherichia coli</i>.

<p>Measured parameters for the GTPase activity and polymerization of FtsZ from <i>Escherichia coli</i>.</p

Global analysis of the critical concentration using the integrated van′t Hoff equation.

<p>The combined data obtained with the GTP hydrolysis and polymerization assays were fit to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.e008" target="_blank">Eq 6</a> using nonlinear regression (solid lines), for mesophilic EcFtsZ (A) and thermophilic MjFtsZ (B). The fitting coefficients for EcFtsZ are: <i>a</i> = -787.59, <i>b</i> = 38,745 and <i>c</i> = 117.86, and the coefficients obtained for MjFtsZ: <i>a</i> = 776.24, <i>b</i> = -40,253 and <i>c</i> = -110.53. The temperature-dependent parameters Δ<i>H</i>⁰ and Δ<i>S</i>⁰ were calculated using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.e010" target="_blank">Eq 7</a> (Panels C and D), as well as the temperature-independent heat capacity change Δ<i>C</i>_<i>p</i> (see text).</p

Measured parameters for the GTPase activity and polymerization of FtsZ from <i>Methanocaldococcus jannaschii</i>.

<p>Measured parameters for the GTPase activity and polymerization of FtsZ from <i>Methanocaldococcus jannaschii</i>.</p

Eyring plots of the GTPase activity and polymerization of FtsZ.

<p>Top row, mesophilic EcFtsZ. Bottom row, thermophilic MjFtsZ. The kinetic rates of GTP hydrolysis, <i>k_cat</i> (A and C), and filament depolymerization, <i>k_depol</i> (B and D), are plotted as a function of temperature. The apparent enthalpies (Δ<i>H</i>^0‡) and entropies (Δ<i>S</i>^0‡) of the transition state were calculated by nonlinear regression using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.e006" target="_blank">Eq 4</a> (solid lines), and the best-fit values are reported in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.t003" target="_blank">Table 3</a>.</p

The morphology of FtsZ polymers was characterized by negative-stain transmission electron microscopy.

<p>Top row, 10 μM EcFtsZ was polymerized at 10, 20 and 30°C (A-C). Bottom row, 10 μM MjFtsZ was polymerized at 40, 60 and 80°C (D–F). The arrowheads in D point to examples of short and curved polymers. The scale bars represent 100 and 500 nm for the top and bottom rows, respectively (black bars).</p

Temperature dependence of the GTP hydrolysis rates of FtsZ.

<p>The effect of temperature and protein concentration on the GTPase activity of FtsZ was examined for mesophilic EcFtsZ (A) and for thermophilic MjFtsZ (B). The catalytic constant <i>k_cat</i> was determined from the slopes of the linear regressions indicated by the solid lines (the substrate was used at saturating concentrations). The critical concentrations C_C-GTPase were obtained from the intersection of the linear regressions with the protein concentration axis. The symbols and error bars are the averages and the standard deviations from triplicate samples. The calculated values of C_C-GTPase and <i>k_cat</i> are presented in Tables <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.t001" target="_blank">1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185707#pone.0185707.t002" target="_blank">2</a>.</p

Transition state enthalpy, entropy and free energy of FtsZ assembly.

<p>Transition state enthalpy, entropy and free energy of FtsZ assembly.</p