The plant-specific FYVE-domain-containing protein FYVE4,a component of the endosomal sorting complex required for transport III(ESCRT-III),participates in membrane protein sorting.However,the mechanism by which FYVE4 ...The plant-specific FYVE-domain-containing protein FYVE4,a component of the endosomal sorting complex required for transport III(ESCRT-III),participates in membrane protein sorting.However,the mechanism by which FYVE4 coordinates plant growth responses to environmental stress remains unclear.In this study,we reveal a novel function of FYVE4 in positively regulating plant salt resistance by modulating the Salt Overly Sensitive(SOS)signaling pathway.FYVE4 enhances SOS1 phosphorylation by promoting SOS1-SOS2 interactions during salt stress.Loss of FYVE4 reduces the SOS1-SOS2 association,leading to decreased SOS1 phosphorylation and increased plant sensitivity to salt stress.Notably,overexpression of SOS1 does not rescue the salt-sensitive phenotype of fyve4-1,whereas SOS2 overexpression does.In summary,our findings highlight the critical role of FYVE4 in promoting SOS1-SOS2 interactions to mitigate salt stress and reveal a previously unrecognized function of FYVE4 in abiotic stress responses,extending beyond its established role in membrane trafficking regulation.展开更多
The protein kinase SOS2 （Salt Overly Sensitive 2） is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS...The protein kinase SOS2 （Salt Overly Sensitive 2） is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS2 is autophosphorylated in vitro, but the autophosphorylation site and its role in salt tolerance are not known. In this study, we identified an autophosphorylation site in SOS2 and analyzed its role in the responses of Arabidopsis to salt stress. Mass spectrometry analysis showed that Ser 228 of SOS2 is autophosphorylated. When this site was mutated to Ala, the autophosphorylation rate of SOS2 decreased. The substrate phosphorylation by the mutated SOS2 was also less than that by the wild-type SOS2. In contrast, changing Ser228 to Asp to mimic the autophosphorylation enhanced substrate phosphorylation by SOS2. Complementation tests in a sos2 mutant showed that the S228A but not the $228D mutation partially disrupted the function of SOS2 in salt tolerance. We also show that activation loop phosphorylation at Thr168 and autophosphorylation at Ser228 cannot substitute for each other, suggesting that both are required for salt tolerance. Our results indicate that Ser 228 of SOS2 is autophosphorylated and that this autophosphorylation is important for SOS2 function under salt stress.展开更多
基金supported by grants from the Guangdong Province(grant nos.2021A1515010913 and 2024B1515020043)the National Natural Science Foundation of China(grant no.32370329)to H.L.+4 种基金the China Postdoctoral Science Foundation(grant no.2022M721220)and the Guangdong Basic and Applied Basic Research Foundation(grant no.2023A1515110972)to C.L.the National Natural Science Foundation of China(NSFC,grant nos.32061160467,32270291,and 31870171)the Fok Ying-Tong Education Foundation for Young Teachers in Higher Education Institutions of China(grant no.171014)to C.G.the Open Competition Program of the Top Ten Critical Priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(2022SDZG05)as well as the Guangdong Province Rural Revitalization Strategy Special Funding for Seed Industry Vitalization to Y.Z.
文摘The plant-specific FYVE-domain-containing protein FYVE4,a component of the endosomal sorting complex required for transport III(ESCRT-III),participates in membrane protein sorting.However,the mechanism by which FYVE4 coordinates plant growth responses to environmental stress remains unclear.In this study,we reveal a novel function of FYVE4 in positively regulating plant salt resistance by modulating the Salt Overly Sensitive(SOS)signaling pathway.FYVE4 enhances SOS1 phosphorylation by promoting SOS1-SOS2 interactions during salt stress.Loss of FYVE4 reduces the SOS1-SOS2 association,leading to decreased SOS1 phosphorylation and increased plant sensitivity to salt stress.Notably,overexpression of SOS1 does not rescue the salt-sensitive phenotype of fyve4-1,whereas SOS2 overexpression does.In summary,our findings highlight the critical role of FYVE4 in promoting SOS1-SOS2 interactions to mitigate salt stress and reveal a previously unrecognized function of FYVE4 in abiotic stress responses,extending beyond its established role in membrane trafficking regulation.
文摘The protein kinase SOS2 （Salt Overly Sensitive 2） is essential for salt-stress signaling and tolerance in Arabidopsis. SOS2 is known to be activated by calcium-SOS3 and by phosphorylation at its activation loop. SOS2 is autophosphorylated in vitro, but the autophosphorylation site and its role in salt tolerance are not known. In this study, we identified an autophosphorylation site in SOS2 and analyzed its role in the responses of Arabidopsis to salt stress. Mass spectrometry analysis showed that Ser 228 of SOS2 is autophosphorylated. When this site was mutated to Ala, the autophosphorylation rate of SOS2 decreased. The substrate phosphorylation by the mutated SOS2 was also less than that by the wild-type SOS2. In contrast, changing Ser228 to Asp to mimic the autophosphorylation enhanced substrate phosphorylation by SOS2. Complementation tests in a sos2 mutant showed that the S228A but not the $228D mutation partially disrupted the function of SOS2 in salt tolerance. We also show that activation loop phosphorylation at Thr168 and autophosphorylation at Ser228 cannot substitute for each other, suggesting that both are required for salt tolerance. Our results indicate that Ser 228 of SOS2 is autophosphorylated and that this autophosphorylation is important for SOS2 function under salt stress.
