Figure S1.
Nucleotide binding and GTP hydrolysis of OPA1. (A) Binding affinity of GMPPNP and GMPPCP for WT OPA1-MGD was measured by ITC in the presence of 150 mM KCl or NaCl. 2 mM nucleotides were titrated stepwise into 0.1 mM protein. The KD, if calculatable, is given in the inset. The data are representative of at least three repetitions. (B) GTPase activity of OPA1-MGD was measured in the presence of 250 mM NaCl or KCl and 4 mM MgCl2. The indicated concentrations of OPA1 were used for each sample. GTP hydrolysis was measured by phosphate release at saturating GTP concentrations (1 mM). Data are presented as the mean ± SD of three measurements and representative of at least three repetitions. (C) As in B, but with the his-tag removed. (D) Sequence comparison of the G2/Switch 1 of OPA1 and Mgm1. Interactions with the catalytic water and bridging water are shown on the left and G319 interactions on the right. (E) As in C, but with the indicated OPA1-MGD.