Fluorescence quenching assay
Fluorescence quenching analysis was performed as previously described(Xu et al., 2015). The purified DHODH protein was incubated with various concentrations of PIP at 4 °C for 1 h and fluorescence spectra were detected using a Cary Eclipse fluorescence spectrophotometer (Agilent Technologies, CA, USA). Excitation wavelength was set at 280 nm and emission spectra ranging from 285 to 600 nm was recorded.