Figure 7. AtLYK5 forms a homodimer.

(A) Homodimeriztion of AtLYK5 is independent on the presence of CERK1 or chitin elicitation. AtLYK5-HA and AtLYK5-Myc, or AtCERK1-HA and AtCERK1-Myc were co-expressed in protoplasts made from Col-0 and Atcerk1 mutant plants. Protoplasts were harvested before (−) or 15 min after (+) treatment with 1 µM different chitin oligomers. Co-immunoprecipitation was made using anti-Myc antibody. (B) Dithiothreitol (DTT) treatment converts AtLYK5 dimer to monomer. Crude protein was extracted from transgenic Arabidopsis expressing AtLYK5-HA in Atlyk5-2 mutant plants. Plant tissues were harvested before (−) and 15 min after (+) treatment with 1 µM chitooctaose. Crude proteins from these tissues were boiled for 5 min before (−) or after (+) adding 50 mM DTT. Left panel and right panel of the immunoblot detected with anti-HA antibody are from the same gel.

DOI: http://dx.doi.org/10.7554/eLife.03766.020

Figure 7—figure supplement 1. A possible working model of chitin receptor in Arabidopsis.

Before chitin treatment, AtLYK5 is present as a homodimer. After chitin elicitation, AtCERK1 associates with AtLYK5 to form a possible tetremer to mediate chitin signaling, and AtCERK1 will be phosphorylated at the same time. In this model, AtLYK5 (or AtLYK4) serves as a chitin perception, while AtCERK1 is responsible for chitin signaling transduction due to lack of kinase activity of AtLYK5 (or AtLYK4).

DOI: http://dx.doi.org/10.7554/eLife.03766.021