Purification, crystallization and preliminary X-ray diffraction analysis of an oomycete-derived Nep1-like protein

The elicitor protein Nep1-like protein from the plant pathogen Pythium aphanidermatum was purified and crystallized using the hanging-drop vapour-diffusion method. A native data set was collected to 1.35 angstrom resolution at 100 K using synchrotron radiation. Since selenomethionine-labelled protein did not crystallize under the original conditions, a second crystal form was identified that yielded crystals that diffracted to 2.1 angstrom resolution. A multiple-wavelength anomalous dispersion (MAD) experiment was performed at 100 K and all four selenium sites were identified, which allowed solution of the structure.