题目：硝酸盐感受器NRT1.1与受体激酶在低氮下调控质子泵活性的分子机制

主讲：武旭娜 研究员（云南大学）

时间：12月11日（周四）11:20-12:20

会议地点：慧园4栋301

个人简介：武旭娜，云南大学生命科学学院，研究员，博士生导师，入选云南省青年人才项目。2012年德国马普所获博士学位，随后在德国霍恩海姆大学从事博士后研究。2019年底加入云南大学，主要研究方向为解析植物膜蛋白在感知碳氮信号及碳氮转运中的功能，植物功能蛋白质组学。在Current Biology等国际权威期刊上发表多篇研究论文。Springer-Nature主编出版了学术专著《Plant Phosphoproteomics》。中国遗传学会农业蛋白质组学分会副主任，中国生物化学与分子生物学学会蛋白质组学专业分会理事，New Crops杂志青年编委。

报告摘要：Mild low nitrogen deficiency (LN) modulates apoplamtic pH in the lateral root elongation zone (LREZ). NRT1.1, a critical nitrate transceptor in the plasma membrane, controls H+-ATPase driven acidification of the apoplast under LN though phosphorylation of the PM H⁺-ATPase AHA2 at S899 (thereby inhibiting activity) by receptor kinase QSK1. We also found that NRT1.1 and QSK1 indirectly induce the phosphorylation of AHA2 at T947, which increases activity, while the kinase involved in phosphorylating T947 remained unclear. Through PL-MS, we identified Arabidopsis co-receptor BAK1 as a crucial player in NRT1.1-QSK1-mediated AHA2 activation under LN. Interestingly, we found that NRT1.1-BAK1 interaction inactivates AHA2 activity under HN. However, With LN binding to NRT1.1, activated QSK1 can disrupt NRT1.1-BAK1 interaction to release BAK1 from NRT1.1 and recruits a proportion of BAK1 to form a complex, thus directing BAK1 to activate AHA2 through phosphorylation of AHA2 at T947 site. Thus, our findings uncover a dual role of QSK1: one to release BAK1 from NRT1.1 and maintain a subset of BAK1 in the complex to activate AHA2, and the other to phosphorylate S899 to inhibit AHA2 activity. Our results reveal a new mechanism showing how receptor kinase QSK1 connects NRT1.1 and BAK1 to fine-tune the PM H+-ATPase activity in response to LN. In summary, both QSK1 and BAK1 function downstream of NRT1.1 to synergistically orchestrate AHA2 activity and maintain NRT1.1-mediated pH homeostasis of the LREZ under LN.