Suppression mechanisms mediated by transcriptional repressors commonly exist in diverse phytohormone signaling pathways.In Arabidopsis thaliana,JASMONATE-ZIM DOMAIN(JAZ)proteins are transcriptional repressors that fun...Suppression mechanisms mediated by transcriptional repressors commonly exist in diverse phytohormone signaling pathways.In Arabidopsis thaliana,JASMONATE-ZIM DOMAIN(JAZ)proteins are transcriptional repressors that function as negative regulators of diverse JA responses.Novel Interactor of JAZ(NINJA)is an adaptor protein connecting JAZs with the co-repressor,TOPLESS(TPL),to mediate gene repression in JA-dependent root growth inhibition and defense pathways.However,whether NINJA or other adaptor proteins are employed in other JA-responsive biological processes remains to be elucidated.In the present study,we demonstrate that a previously uncharacterized protein,ECAP(EAR motif-Containing Adaptor Protein),directly interacts with JAZ6 and JAZ8 and enhances their transcriptional repression activities.We provide evidence that ECAP is a novel adaptor protein for JAZ6/8 recruitment of the transcriptional co-repressor,TOPLESS-RELATED 2(TPR2),into a transcriptional repressor complex that represses the WD-repeat/bHLH/MYB complex,an important transcriptional activator in the JA-dependent anthocyanin biosynthesis pathway.Our findings,together with previous reports,reveal that specific adaptor proteins play a critical role in distinct JA responses by pairing different JAZs(which possess overlapping but also specific functions)with the general co-repressors,TPL and TPRs.展开更多
ron(Fe)homeostasis in plant cells is crucial for crop productivity and quality.An intricate transcriptional network involving numerous basic Helix-Loop-Helix(bHLH)transcription factors has been proposed to control Fe ...ron(Fe)homeostasis in plant cells is crucial for crop productivity and quality.An intricate transcriptional network involving numerous basic Helix-Loop-Helix(bHLH)transcription factors has been proposed to control Fe homeostasis.In the present study,we characterized rice(Oryza sativa)OsbHLH062,a member of the IVb subgroup of the bHLH family,demonstrating that it negatively regulates Fe-deficiency responses.OsbHLH062 represses transcription by recruiting TOPLESS/TOPLESS-RELATED co-repressors(TPL/TPRs)through its ethylene-responsive element binding factor-associated amphiphilic repression(EAR)motif.Under Fe deficiency,the expression of OsbHLH062 is upregulated in roots and downregulated in shoots.Overexpression of OsbHLH062 leads to decreased Fe accumulation in the shoot.Furthermore,OsbHLH062 interacts with POSITIVE REGULATOR OF IRON HOMEOSTASIS 1(OsPRI1)and inhibits its transactivation activity,thereby negatively regulating the expression of many Fe homeostasis-related genes.These results indicate an important role for OsbHLH062 in regulating Fe homeostasis by negatively regulating Fe deficiency responses in rice.This knowledge will aid in the design of Fe-biofortified rice plants that can help to address the global issue of Fe deficiency.展开更多
基金supported by the National Natural Science Foundation of China(grant no.31872662 and 91854119 to Y.F.)China Postdoctoral Science Foundation grant(2018M641532 to C.L.).
文摘Suppression mechanisms mediated by transcriptional repressors commonly exist in diverse phytohormone signaling pathways.In Arabidopsis thaliana,JASMONATE-ZIM DOMAIN(JAZ)proteins are transcriptional repressors that function as negative regulators of diverse JA responses.Novel Interactor of JAZ(NINJA)is an adaptor protein connecting JAZs with the co-repressor,TOPLESS(TPL),to mediate gene repression in JA-dependent root growth inhibition and defense pathways.However,whether NINJA or other adaptor proteins are employed in other JA-responsive biological processes remains to be elucidated.In the present study,we demonstrate that a previously uncharacterized protein,ECAP(EAR motif-Containing Adaptor Protein),directly interacts with JAZ6 and JAZ8 and enhances their transcriptional repression activities.We provide evidence that ECAP is a novel adaptor protein for JAZ6/8 recruitment of the transcriptional co-repressor,TOPLESS-RELATED 2(TPR2),into a transcriptional repressor complex that represses the WD-repeat/bHLH/MYB complex,an important transcriptional activator in the JA-dependent anthocyanin biosynthesis pathway.Our findings,together with previous reports,reveal that specific adaptor proteins play a critical role in distinct JA responses by pairing different JAZs(which possess overlapping but also specific functions)with the general co-repressors,TPL and TPRs.
基金supported by the National Natural Science Foundation of China(32172668 to LZ.and 32300227 to WW)the Natural Science Foundation of Jiangsu Province(BK20242063 to L.Z.and BK20230989 to W.W.).
文摘ron(Fe)homeostasis in plant cells is crucial for crop productivity and quality.An intricate transcriptional network involving numerous basic Helix-Loop-Helix(bHLH)transcription factors has been proposed to control Fe homeostasis.In the present study,we characterized rice(Oryza sativa)OsbHLH062,a member of the IVb subgroup of the bHLH family,demonstrating that it negatively regulates Fe-deficiency responses.OsbHLH062 represses transcription by recruiting TOPLESS/TOPLESS-RELATED co-repressors(TPL/TPRs)through its ethylene-responsive element binding factor-associated amphiphilic repression(EAR)motif.Under Fe deficiency,the expression of OsbHLH062 is upregulated in roots and downregulated in shoots.Overexpression of OsbHLH062 leads to decreased Fe accumulation in the shoot.Furthermore,OsbHLH062 interacts with POSITIVE REGULATOR OF IRON HOMEOSTASIS 1(OsPRI1)and inhibits its transactivation activity,thereby negatively regulating the expression of many Fe homeostasis-related genes.These results indicate an important role for OsbHLH062 in regulating Fe homeostasis by negatively regulating Fe deficiency responses in rice.This knowledge will aid in the design of Fe-biofortified rice plants that can help to address the global issue of Fe deficiency.
