野油菜黄单胞菌效应蛋白AvrXccC与拟南芥BIK1在植物体内相互作用

 AvrXccC是野油菜黄单胞菌Xcc8004的一个III型分泌效应蛋白。前期研究发现AvrXccC在拟南芥rar1突变体上发挥毒性功能,并且抑制植物的先天免疫反应。但是,AvrXccC在植物体内的毒性靶标还不清楚。本研究发现AvrXccC与植物体内的蛋白激酶BIK1发生特异的相互作用。然而,在拟南芥原生质体中,AvrXccC 并不能抑制鞭毛蛋白诱导的BIK1迁移,表明AvrXccC不是通过抑制BIK1的磷酸化来发挥功能的。有趣的是,AvrXccC可以在体外直接被BIK1磷酸化,我们推测AvrXccC可能作为BIK1的底物从而干扰了鞭毛蛋白诱导的先天免疫反应。

Xanthomonas campestris pv. campestris effector protein AvrXccC interacts with the cytoplasmic kinase BIK1

AvrXccC is a type III secretion systems (TTSS) effector protein of Xanthomonas campestris pv. campestris (Xcc) strain 8004. Previous studies have shown that AvrXccC acts as a virulence factor in Arabidopsis rar1 mutant, and suppresses flg22-induced innate immunity. However, it remains unclear about the virulence target of AvrXccC in plants. Here, we found AvrXccC specifically interacted with the cytoplasmic kinase BIK1 in vitro and in vivo. Furthermore, AvrXccC did not suppress flg22-induced BIK1 migration in protoplast, indicating that AvrXccC is not a regulator of BIK1 phosphorylation. Interestingly, we found that AvrXccC was phosphorylated by BIK1 in vitro, suggesting that AvrXccC probably acts as a substrate of BIK1 to interfere with the plant innate immunity.