Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China.
The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China.
PLoS Genet. 2023 May 15;19(5):e1010748. doi: 10.1371/journal.pgen.1010748. eCollection 2023 May.
The rice blast fungus Magnaporthe oryzae forms specialized infectious structures called appressoria that breach host cells to initiate infection. Previous studies demonstrated that the regulator of G-protein signaling (RGS)-like protein MoRgs7 undergoes endocytosis upon fungal sensing of hydrophobic environmental cues to activate cAMP signaling required for appressorium formation. However, the mechanism by which MoRgs7 internalizes and its fate remains undetermined. We here show that MoSep1, a conserved protein kinase of Mitotic Exit Network (MEN), phosphorylates MoRgs7 to regulate its function. MoRgs7 phosphorylation determines its interaction with MoCrn1, a coronin-like actin-binding protein homolog that also modulates the internalization of MoRgs7. Importantly, the endocytic transport of MoRgs7 is critical for its GTPase-activating protein (GAP) function important in cAMP signaling. Together, our findings revealed a novel mechanism by which M. oryzae activates MoRgs7-mediated hydrophobic cue-sensing signal transduction involving protein phosphorylation and endocytic transport to govern appressorium formation and fungal pathogenicity.
稻瘟病菌 Magnaporthe oryzae 形成专门的感染结构，称为附着胞，突破宿主细胞以启动感染。以前的研究表明，G 蛋白信号调节因子（RGS）样蛋白 MoRgs7 在真菌感知疏水环境信号时经历内吞作用，以激活对附着胞形成所必需的 cAMP 信号。然而，MoRgs7 内化的机制及其命运仍未确定。我们在这里表明，Mitotic Exit Network (MEN) 的保守蛋白激酶 MoSep1 磷酸化 MoRgs7 以调节其功能。MoRgs7 的磷酸化决定了它与 MoCrn1 的相互作用，MoCrn1 是一种 coronin 样肌动蛋白结合蛋白同源物，也调节 MoRgs7 的内化。重要的是，MoRgs7 的内吞运输对于其 GTP 酶激活蛋白（GAP）功能至关重要，该功能在 cAMP 信号中起重要作用。总之，我们的发现揭示了一种新的机制，即稻瘟病菌激活由 MoRgs7 介导的疏水性感应信号转导，涉及蛋白磷酸化和内吞运输，以控制附着胞形成和真菌致病性。
