Light and the heterotrimeric G-protein are known to antagonistically regulate photomorphogenesis in Arabidopsis. However, whether light and G-protein coordinate the regulation of photomorphogenesis is largely unknown....Light and the heterotrimeric G-protein are known to antagonistically regulate photomorphogenesis in Arabidopsis. However, whether light and G-protein coordinate the regulation of photomorphogenesis is largely unknown. Here we show that the blue light photoreceptor cryptochrome 1 （CRY1） physically inter-acts with the G-protein β subunit, AGB1, in a blue light-dependent manner. We also show that AGB1 directly interacts with HY5, a basic leucine zipper transcriptional factor that acts as a critical positive regulator of photomorphogenesis, to inhibit its DNA-binding activity. Genetic studies suggest that CRY1 acts partially through AGB1, and AGB1 acts partially through HY5 to regulate photomorphogenesis. Moreover, we demonstrate that blue light-triggered interaction of CRY1 with AGB1 promotes the dissociation of HY5 from AGB1. Our results suggest that the CRY1 signaling mechanism involves positive regulation of the DNA-binding activity of HY5 mediated by the CRY1-AGB1 interaction, which inhibits the association of AGB1 with HY5. We propose that the antagonistic regulation of HY5 DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize photomorphogenesis.展开更多
Phytochrome B (phyB), the primary red light photoreceptor, promotes photomorphogenesis in Arabidopsis by interacting with the basic helix-loop-helix transcriptional factor PIF3 and inducing its phosphorylation and deg...Phytochrome B (phyB), the primary red light photoreceptor, promotes photomorphogenesis in Arabidopsis by interacting with the basic helix-loop-helix transcriptional factor PIF3 and inducing its phosphorylation and degradation. Heterotrimeric G proteins are known to regulate various developmental processes in plants and animals. In Arabidopsis, the G-protein β subunit AGB1 is known to repress photomorphogenesis. However, whether and how phyB and AGB1 coordinately regulate photomorphogenesis are largely unknown. Here we show that phyB physically interacts with AGB1 in a red light-dependent manner and that AGB1 interacts directly with PIF3. Moreover, we demonstrate that the AGB1-PIF3 interaction inhibits the association of PIF3 with phyB, leading to reduced phosphorylation and degradation of PIF3, whereas the phyB-AGB1 interaction represses the association of PIF3 with AGB1, resulting in enhaneed phosphorylation and degradation of PIF3. Our results suggest that phyB and AGB1 antagonistically regulate PIF3 stability by dynamically interacting with each other and PIF3. This dynamic mechanism may allow plants to balanee phyB and G-protein signaling to optimize photomorphogenesis.展开更多
Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabi...Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabidopsis, cryptochrome 1(CRY1) and the G-protein β subunit AGB1 act antagonistically to regulate stomatal development.The molecular mechanism by which CRY1 and AGB1 regulate this process remains unknown.Here, we show that Arabidopsis CRY1 acts partially through AGB1, and AGB1 acts through SPEECHLESS(SPCH), a master transcription factor that drives stomatal initiation and proliferation, to regulate stomatal development. We demonstrate that AGB1 physically interacts with SPCH to block the b HLH DNA-binding domain of SPCH and inhibit its DNA-binding activity. Moreover, we demonstrate that photoexcited CRY1 represses the interaction of AGB1 with SPCH to release AGB1 inhibition of SPCH DNA-binding activity, leading to the expression of SPCH-target genes promoting stomatal development. Taken together, our results suggest that the mechanism by which CRY1 promotes stomatal development involves positive regulation of the DNA-binding activity of SPCH mediated by CRY1 inhibition of the AGB1-SPCH interaction. We propose that the antagonistic regulation of SPCH DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize stomatal density and pattern.展开更多
The plant hormones salicylic acid(SA)and jasmonic acid(JA)act in mutual negative-feedback regulation to balance plant growth-defense trade-off.Heterotrimeric Gα-Gβ-Gγproteins are hubs that regulate defense signalin...The plant hormones salicylic acid(SA)and jasmonic acid(JA)act in mutual negative-feedback regulation to balance plant growth-defense trade-off.Heterotrimeric Gα-Gβ-Gγproteins are hubs that regulate defense signaling.In Arabidopsis,the Gα(GPA1)and Gβ(AGB1)subunits are required for defense against biotrophic and necrotrophic pathogens;however,the upstream and downstream molecular mechanisms underlying G protein-mediated defense remain largely unclear.In this study,we found that G proteins are primarily negative regulators of JA signaling in response to pathogen attack.Both TCP14 and JAZs are transcriptional regulators in the JA pathways.We revealed that GPA1 interacts with TCP14 within nuclear foci,and AGB1 interacts with TCP14 and most of JAZ regulators,including JAZ3.Mechanistically,GPA1 slows the proteasomal degradation of the G protein-TCP14-JAZ3 complex,a process that is normally promoted by JA and the bacterial virulence effector HopBB1,thus boosting SA-based defense.In turn,GPA1 activity is regulated by JA-induced phosphorylation at a conserved residue located near the nucleotide-binding pocket and other residues within the N-terminalαhelix.The phosphomimic mutations do not affect GTP binding or hydrolysis but enhance GPA1 interaction with TCP14 and JAZ3,thereby preventing their degradation.This newly discovered phosphorylation-dependent mechanism of de-sequestering G protein partners to modulate transcriptional regulation may extend to both yeast and human cells.展开更多
基金This work was supported by The National Natural Science Foundation of China grants to H.-Q.Y. （31530085, 91217307, and 90917014） and to H.L. Lian （31570282 and 31170266）, and the National Key Research and Devel- opment Program of China grant （2017YFA0503800）.
文摘Light and the heterotrimeric G-protein are known to antagonistically regulate photomorphogenesis in Arabidopsis. However, whether light and G-protein coordinate the regulation of photomorphogenesis is largely unknown. Here we show that the blue light photoreceptor cryptochrome 1 （CRY1） physically inter-acts with the G-protein β subunit, AGB1, in a blue light-dependent manner. We also show that AGB1 directly interacts with HY5, a basic leucine zipper transcriptional factor that acts as a critical positive regulator of photomorphogenesis, to inhibit its DNA-binding activity. Genetic studies suggest that CRY1 acts partially through AGB1, and AGB1 acts partially through HY5 to regulate photomorphogenesis. Moreover, we demonstrate that blue light-triggered interaction of CRY1 with AGB1 promotes the dissociation of HY5 from AGB1. Our results suggest that the CRY1 signaling mechanism involves positive regulation of the DNA-binding activity of HY5 mediated by the CRY1-AGB1 interaction, which inhibits the association of AGB1 with HY5. We propose that the antagonistic regulation of HY5 DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize photomorphogenesis.
基金The National Natural Science Foundation of China grants to H.-Q.Y.(31530085) and H.L.L (31570282 and 31170266)The National Key Research and Development Program of China grant (2017YFA0503802)the Science and Technology Commission of Shanghai Municipality grant (18DZ2260500).
文摘Phytochrome B (phyB), the primary red light photoreceptor, promotes photomorphogenesis in Arabidopsis by interacting with the basic helix-loop-helix transcriptional factor PIF3 and inducing its phosphorylation and degradation. Heterotrimeric G proteins are known to regulate various developmental processes in plants and animals. In Arabidopsis, the G-protein β subunit AGB1 is known to repress photomorphogenesis. However, whether and how phyB and AGB1 coordinately regulate photomorphogenesis are largely unknown. Here we show that phyB physically interacts with AGB1 in a red light-dependent manner and that AGB1 interacts directly with PIF3. Moreover, we demonstrate that the AGB1-PIF3 interaction inhibits the association of PIF3 with phyB, leading to reduced phosphorylation and degradation of PIF3, whereas the phyB-AGB1 interaction represses the association of PIF3 with AGB1, resulting in enhaneed phosphorylation and degradation of PIF3. Our results suggest that phyB and AGB1 antagonistically regulate PIF3 stability by dynamically interacting with each other and PIF3. This dynamic mechanism may allow plants to balanee phyB and G-protein signaling to optimize photomorphogenesis.
基金This work was supported by The National Natural Science Foundation of China grants(31530085,31900609,31900207,32000183)The National Key Research and Development Program of China grant(2017YFA0503802)The Science and Technology Commission of Shanghai Municipality grant(18DZ2260500)。
文摘Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabidopsis, cryptochrome 1(CRY1) and the G-protein β subunit AGB1 act antagonistically to regulate stomatal development.The molecular mechanism by which CRY1 and AGB1 regulate this process remains unknown.Here, we show that Arabidopsis CRY1 acts partially through AGB1, and AGB1 acts through SPEECHLESS(SPCH), a master transcription factor that drives stomatal initiation and proliferation, to regulate stomatal development. We demonstrate that AGB1 physically interacts with SPCH to block the b HLH DNA-binding domain of SPCH and inhibit its DNA-binding activity. Moreover, we demonstrate that photoexcited CRY1 represses the interaction of AGB1 with SPCH to release AGB1 inhibition of SPCH DNA-binding activity, leading to the expression of SPCH-target genes promoting stomatal development. Taken together, our results suggest that the mechanism by which CRY1 promotes stomatal development involves positive regulation of the DNA-binding activity of SPCH mediated by CRY1 inhibition of the AGB1-SPCH interaction. We propose that the antagonistic regulation of SPCH DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize stomatal density and pattern.
基金supported by The Division of Chemical Sciences,Geosciences,and Biosciences,Office of Basic Energy Sciences of the US Department of Energy through grant DE-FG02-05er15671A.M.J.Funding was also provided by NIGMS(R01GM065989)and NSF(MCB-0718202 and IOS-2034929)awarded to A.M.J.,NIH grant(R35GM118105)awarded to H.G.D.,grant PID2021-1260060OB-I00 funded by MCIN/AEI/10.13039/501100011033by“ERDFAway of making Europe"to A.M.and L.J.
文摘The plant hormones salicylic acid(SA)and jasmonic acid(JA)act in mutual negative-feedback regulation to balance plant growth-defense trade-off.Heterotrimeric Gα-Gβ-Gγproteins are hubs that regulate defense signaling.In Arabidopsis,the Gα(GPA1)and Gβ(AGB1)subunits are required for defense against biotrophic and necrotrophic pathogens;however,the upstream and downstream molecular mechanisms underlying G protein-mediated defense remain largely unclear.In this study,we found that G proteins are primarily negative regulators of JA signaling in response to pathogen attack.Both TCP14 and JAZs are transcriptional regulators in the JA pathways.We revealed that GPA1 interacts with TCP14 within nuclear foci,and AGB1 interacts with TCP14 and most of JAZ regulators,including JAZ3.Mechanistically,GPA1 slows the proteasomal degradation of the G protein-TCP14-JAZ3 complex,a process that is normally promoted by JA and the bacterial virulence effector HopBB1,thus boosting SA-based defense.In turn,GPA1 activity is regulated by JA-induced phosphorylation at a conserved residue located near the nucleotide-binding pocket and other residues within the N-terminalαhelix.The phosphomimic mutations do not affect GTP binding or hydrolysis but enhance GPA1 interaction with TCP14 and JAZ3,thereby preventing their degradation.This newly discovered phosphorylation-dependent mechanism of de-sequestering G protein partners to modulate transcriptional regulation may extend to both yeast and human cells.
