Double fertilization in angiosperms requires the targeted delivery of immotile sperm to the eggs through pollen tubes. The polarity of tip-growing pollen tubes is maintained through dynamic association of active Rho G...Double fertilization in angiosperms requires the targeted delivery of immotile sperm to the eggs through pollen tubes. The polarity of tip-growing pollen tubes is maintained through dynamic association of active Rho GTPases of plants （ROP-GTP） with the apical plasma membrane. Guanine nucleotide exchange factors for ROPs （RopGEFs） catalyze the activation of ROPs and thereby affect spatiotemporal ROP signaling. Whereas RopGEFs have been found to be phosphorylated proteins, the kinases responsible for their phos- phorylation in v/vo and biological consequences of RopGEF phosphorylation in pollen tube growth remain unclear. We report here that the Arabidopsis AGC1.5 subfamily of cytoplasmic kinases is critical for the restricted localization of ROP-GTP during pollen tube growth. Loss of AGCI.5 and AGC1.7 functions resulted in the mistargeting of active ROPs and defective events downstream of ROP signaling in pollen tubes. AGCI.5 interacts with RopGEFs via their catalytic PRONE domain and phosphorylates RopGEFs at a conserved Ser residue of PRONE domain. Loss of AGC1.5 and AGC1.7 functions resulted in the mistargeting of RopGEFs in pollen tubes, similar to the phenotype caused by the mutation that renders RopGEFs non-phosphorylatable by AGC1.5. Collectively, our results provide mechanistic insights into the spatiotem- poral activation of ROPs during the polar growth of pollen tubes.展开更多
Most eukaryotic cells are polarized.Common toolbox regulating cell polarization includes Rho gua-nosine triphosphatases(GTPases),in which spatio-temporal activation is regulated by a plethora of reg-ulators.Rho of pla...Most eukaryotic cells are polarized.Common toolbox regulating cell polarization includes Rho gua-nosine triphosphatases(GTPases),in which spatio-temporal activation is regulated by a plethora of reg-ulators.Rho of plants(ROPs)are the only Rho GTPases in plants.Although vesicular trafficking was hinted in the regulation of ROPs,it was unclear where vesicle-carried ROP starts,whether it is dynamically regulated,and which components participate in vesicle-mediated ROP targeting.In addition,although vesicle trafficking and guanine nucleotide inhibitor(GDI)pathways in Rho signaling have been extensively studied in yeast,it is unknown whether the two pathways interplay.Unclear are also cellular and developmental con-sequences of their interaction in multicellular organisms.Here,we show that the dynamic targeting of ROP through vesicles requires coat protein complexⅡand ADP-ribosylation factor 1-mediated post-Golgi trafficking.Trafficking of vesicle-carried ROPs between the plasma membrane and the trans-Golgi network is mediated through adaptor protein 1 and sterol-mediated endocytosis.Finally,we show that GDI and vesicle trafficking synergistically regulate cell polar-ization and ROP targeting,suggesting that the estab-lishment and maintenance of cell polarity is regulated by an evolutionarily conserved mechanism.展开更多
Protein S-acylation is a reversible posttranslational modification that involves the addition of a 16-carbon saturated lipid group,usually a palmitate group,to cysteine residues of a substrate protein(Hemsley and Grie...Protein S-acylation is a reversible posttranslational modification that involves the addition of a 16-carbon saturated lipid group,usually a palmitate group,to cysteine residues of a substrate protein(Hemsley and Grierson 2008;Hemsley et al.2013;Running 2014).展开更多
基金This research was supported by the National Natural Science Foundation of China （31471304 to Y.Z. 31771558 to S.L.）, Natural Science Foundation of Shandong Province （ZR2014CM027 to S.L.）, China Postdoctoral Science Foundation （2018M632698 to E.L.）, and Research Grants Council of Hong Kong （AoE/M-05/12 and C4011-14R）. Y.Z. was partially supported by the Tai-Shan Scholar program from the Shandong Provinciak Government.
文摘Double fertilization in angiosperms requires the targeted delivery of immotile sperm to the eggs through pollen tubes. The polarity of tip-growing pollen tubes is maintained through dynamic association of active Rho GTPases of plants （ROP-GTP） with the apical plasma membrane. Guanine nucleotide exchange factors for ROPs （RopGEFs） catalyze the activation of ROPs and thereby affect spatiotemporal ROP signaling. Whereas RopGEFs have been found to be phosphorylated proteins, the kinases responsible for their phos- phorylation in v/vo and biological consequences of RopGEF phosphorylation in pollen tube growth remain unclear. We report here that the Arabidopsis AGC1.5 subfamily of cytoplasmic kinases is critical for the restricted localization of ROP-GTP during pollen tube growth. Loss of AGCI.5 and AGC1.7 functions resulted in the mistargeting of active ROPs and defective events downstream of ROP signaling in pollen tubes. AGCI.5 interacts with RopGEFs via their catalytic PRONE domain and phosphorylates RopGEFs at a conserved Ser residue of PRONE domain. Loss of AGC1.5 and AGC1.7 functions resulted in the mistargeting of RopGEFs in pollen tubes, similar to the phenotype caused by the mutation that renders RopGEFs non-phosphorylatable by AGC1.5. Collectively, our results provide mechanistic insights into the spatiotem- poral activation of ROPs during the polar growth of pollen tubes.
基金We thank Prof.Liam Dolan for the scn1-1 seeds,XianSheng Zhang for PIN1:GFP,PIN2:GFP seeds,Shu-ZhenMen for the cpi1-1 seeds,and the ABRC for other plantmaterials.This work was supported by theNational Natural Science Foundation of China(31701224 to F.G.,31871422 and 31625003 to Y.Z.,31771558 and 31970332 to S.L.).Y.Z.'s laboratory ispartially supported by Tai-Shan Scholar Program byShandong Provincial Government.
文摘Most eukaryotic cells are polarized.Common toolbox regulating cell polarization includes Rho gua-nosine triphosphatases(GTPases),in which spatio-temporal activation is regulated by a plethora of reg-ulators.Rho of plants(ROPs)are the only Rho GTPases in plants.Although vesicular trafficking was hinted in the regulation of ROPs,it was unclear where vesicle-carried ROP starts,whether it is dynamically regulated,and which components participate in vesicle-mediated ROP targeting.In addition,although vesicle trafficking and guanine nucleotide inhibitor(GDI)pathways in Rho signaling have been extensively studied in yeast,it is unknown whether the two pathways interplay.Unclear are also cellular and developmental con-sequences of their interaction in multicellular organisms.Here,we show that the dynamic targeting of ROP through vesicles requires coat protein complexⅡand ADP-ribosylation factor 1-mediated post-Golgi trafficking.Trafficking of vesicle-carried ROPs between the plasma membrane and the trans-Golgi network is mediated through adaptor protein 1 and sterol-mediated endocytosis.Finally,we show that GDI and vesicle trafficking synergistically regulate cell polar-ization and ROP targeting,suggesting that the estab-lishment and maintenance of cell polarity is regulated by an evolutionarily conserved mechanism.
基金the Natural Science Foundation of Shandong Province(ZR2014CM027 to S.L.)the China Postdoctoral Science Foundation(2015M570605 to S.L.)+1 种基金the National Natural Science Foundation(31771558 to S.L.,31271578,31625003,31871422 to Y.Z.)partially supported by the Tai-Shan Scholar Program by Shandong Provincial Government.
文摘Protein S-acylation is a reversible posttranslational modification that involves the addition of a 16-carbon saturated lipid group,usually a palmitate group,to cysteine residues of a substrate protein(Hemsley and Grierson 2008;Hemsley et al.2013;Running 2014).
