Direct interaction between S-locus receptor kinase and M-locus protein kinase involved in Brassica self-incompatibility signaling
Direct interaction between S-locus receptor kinase and M-locus protein kinase involved in Brassica self-incompatibility signaling
复制标题
DOI：
10.5511/plantbiotechnology.24.185
复制
发表时间：
2007-03-01
影响因子：
1.6
通讯作者：
Takayama, Seiji
中科院分区：
文献类型：
--
作者：
Kakita, Mitsuru;Shimosato, Hiroko;Takayama, Seiji
许多开花植物具有自交不亲和（SI）系统，以防止近亲繁殖。在芸苔属中，SI识别由S-位点的多等位基因复合体（S-单倍型）控制，该复合体编码雄性决定子（S-位点蛋白11（SP11/SCR））和雌性决定子（S-受体激酶（SRK））。自花授粉后，花粉携带的SP11与其同源的柱头SRK受体之间的S-单倍型特异性相互作用诱导柱头乳突细胞中的SI信号，这导致对自花花粉的排斥。我们小组先前对一个自交亲和突变体的遗传分析揭示了膜锚定的细胞质蛋白激酶，M位点蛋白激酶（MLPK）参与SI信号传导。MLPK的质膜定位表明它在SRK附近起作用，但这两种蛋白质之间的生理关系仍然未知。在本研究中，我们使用遗传和生化技术寻找SRK和MLPK之间的直接相互作用。虽然传统的酵母双杂交系统和基于分裂泛素膜的酵母双杂交系统未能检测到SRK和MLPK之间的直接相互作用，但体外磷酸化测定表明SRK的激酶结构域可以有效地磷酸化MLPK。这些结果表明MLPK可能是SRK在芸苔属SI信号转导中的直接靶点。
Many flowering plants possess self-incompatibility (SI) systems to prevent inbreeding. In Brassica, SI recognition is controlled by the multiallelic gene complex (S-haplotypes) at the S-locus, which encodes both the male determinant (S-locus protein 11 (SP11/SCR)) and the female determinant (S-receptor kinase (SRK)). After self-pollination, an S-haplotype specific interaction between pollen-borne SP11 and its cognate stigmatic SRK receptor induces SI signaling in stigma papilla cells, which results in the rejection of the self-pollen. Previous genetic analysis by our group of a self-compatible mutant revealed the involvement of a membrane-anchored cytoplasmic protein kinase, M-locus protein kinase (MLPK), in SI signaling. The plasma membrane localization of MLPK suggests that it functions in the vicinity of SRK, but the physiological relationship between the two proteins remains unknown. In the present study, we looked for a direct interaction between SRK and MLPK using both genetic and biochemical techniques. Although a conventional yeast two-hybrid system and a split-ubiquitin membrane-based yeast two-hybrid system failed to detect a direct interaction between SRK and MLPK, an in vitro phosphorylation assay indicated that the kinase domain of SRK could efficiently phosphorylate MLPK. These results suggest that MLPK could be a direct target of SRK in Brassica SI signaling.