Screen of Receptor-like Kinase OsWAK50 Intracellular Interacting Proteins by Yeast Two-hybrid System*: Screen of Receptor-like Kinase OsWAK50 Intracellular Interacting Proteins by Yeast Two-hybrid System*

The wall-associated kinases (WAKs) belong to a unique subfamily of the receptor-like kinases (RLKs) in plants, named for its tight association with the cell wall. There are 125 OsWAK genes in rice (Oryza saliva), of which OsWAK50 is a typical RLK with an extracellular domain, a transmembrane domain and an intracellular kinase domain. OsWAK50-GFP fusion protein is localized on the cell surface and associated with the cell wall. By the yeast two-hybrid screen, we identified 20 possible OsWAK50 intracellular interacting proteins. Further one to one reverse hybridization indicates that OsSK4, OsSWIB and OsSWI3C interact with OsWAK50 intracellular domain. OsSWIB interacts directly with the kinase domain of OsWAK50, while OsSK4 and OsSWI3C interact with OsWAK50 intracellular domain in a C terminal dependent manner. OsSK4 and OsSWIB can also interact with OsWAK53a, the closest homolog of OsWAK50 in rice, whereas OsSWI3C can not interact with OsWAK53a. The interaction between OsWAK50 and OsSK4, OsWAK.53a and OsSK4 was further confirmed by in, vivo BiFC assay. These results provide important clues for elucidating the molecular mechanisms of OsWAK50 function in rice.