The chitin in fungal cell walls serves as a trigger to initiate plant defenses against pathogenic fungi. Arabidopsis detects these signals through a cell surface chitin receptor whose intracellular kinase domain initiates a signaling cascade in response to chitin that activates the plant’s response to infection. Liu et al. have now solved the crystal structure of the Arabidopsis chitin receptor AtCERK1. The results show how chitin binds to the receptor and suggest that the biological response requires dimerization of the receptor when it binds a chitin oligomer at least seven or eight subunits long.
T. Liu, Z. Liu, C. Song, Y. Hu, Z. Han, J. She, F. Fan, J. Wang, C. Jin, J. Chang, J.-M. Zhou, J. Chai, Chitin-induced dimerization activates a plant immune receptor. Science 336, 1160–1164 (2012). [Abstract] [Full Text]