Crystal structure of human ERK1 bound to a peptide corresponding to the sequence of the Toxoplasma gondii effector protein GRA24 KIM1 sequence at 2.17 Å resolution

The causative agent of toxoplasmosis, the intracellular parasite Toxoplasma gondii, delivers a protein, GRA24, into the cells it infects that interacts with the mitogen-activated protein (MAP) kinase p38α (MAPK14), leading to activation and nuclear translocation of the host kinase and a subsequent inflammatory response that controls the progress of the parasite. This protein also binds the MAP kinase ERK1. We have determined the structure of ERK1 in complex with a peptide with the sequence of the KIM1 motif of GRA24. We have used this sequence to stabilise a complex between ERK2 and its activating MAP2K MEK1 allowing structure determination by cryoEM. The crystal structure provided high resolution confirmation of the GRA24 KIM1 sequence to ERK1.