Protein Translation Enzyme lysyl-tRNA Synthetase Presents a New Target for Drug Development against Causative Agents of Loiasis and Schistosomiasis
Fig 2
Cladosporin activity on worm KRSs.
(A) Chemical structure of cladosporin. Cladosporin (CLD) is composed of a (6,8)-dihydroxyl- isocoumarin ring joined to tetrahydropyran group with a methyl moiety. (B) Inhibition of LlKRS, human-like LlKRS and SmKRS by cladosporin in enzyme assays. Percentage enzyme activity as a function of increasing inhibitor concentration (log scale, 0.01 nM—10 μM) is plotted using non-linear regression. These results represent the mean of three independent experiments performed in triplicates. (C) Protein thermal shift profile of LlKRS, SmKRS and human-like LlKRS (all three at 2 μM) in presence of cladosporin, or AMPPNP or without these two (but with L-lysine). The plot shows measured derivative Tm and data as plotted against fluorescence (arbitrary units) in y-axis and temperature in x-axis. Human-like LlKRS thermal shift at two concentrations of cladosporin 20 μM (in red) and 200 μM (in black) is shown. Mean data from triplicates are presented. (D) Binding data using ITC. Cladosporin was titrated into the protein samples and Kd was determined using Microcal origin software.