Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-...Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.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
Legionella pneumophila is a Gram-negative bacterium ubiquitously present in freshwater environments and causes a serious type of pneumonia called Legionnaires’disease.During infections,L.pneumophila releases over 300...Legionella pneumophila is a Gram-negative bacterium ubiquitously present in freshwater environments and causes a serious type of pneumonia called Legionnaires’disease.During infections,L.pneumophila releases over 300 effector proteins into host cells through an Icm/Dot type IV secretion system to manipulate the host defense system for survival within the host.Notably,certain effector proteins mediate posttranslational modifications(PTMs),serving as useful approaches exploited by L.pneumophila to modify host proteins.Some effectors catalyze the addition of host protein PTMs,while others mediate the removal of PTMs from host proteins.In this review,we summarize L.pneumophila effector-mediated PTMs of host proteins,including phosphorylation,ubiquitination,glycosylation,AMPylation,phosphocholination,methylation,and ADP-ribosylation,as well as dephosphorylation,deubiquitination,deAMPylation,deADP-ribosylation,dephosphocholination,and delipidation.We describe their molecular mechanisms and biological functions in the regulation of bacterial growth and Legionella-containing vacuole biosynthesis and in the disruption of host immune and defense machinery.展开更多
基金supported by Basic Science Research Program and LAMP Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2021R1I1A3054417,2022R1I1A1A01063394,RS-2023-00301974)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2021M3A9I5023695,2022R1A5A1031361)grants from the New Breeding Technologies Development Program(RS-2024-00322125),Rural Development Administration,Republic of Korea。
文摘Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.
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.
基金funded by the National Natural Science Foundation of China(32170185,22011530161,31801166,and 91854101)the Natural Science Foundation of Chongqing,China(cstc2021jcyj-msxmX0030 and CSTB2022NSCQ-MSX0463)+2 种基金the Venture Innovation Support Program for Chongqing Overseas Returnees(cx2022066)the Fundamental Research Funds for the Central Universities(2022CDJYGRH-002)the National Training Program of Innovation and Entrepreneurship for Undergraduates(202210611088).
文摘Legionella pneumophila is a Gram-negative bacterium ubiquitously present in freshwater environments and causes a serious type of pneumonia called Legionnaires’disease.During infections,L.pneumophila releases over 300 effector proteins into host cells through an Icm/Dot type IV secretion system to manipulate the host defense system for survival within the host.Notably,certain effector proteins mediate posttranslational modifications(PTMs),serving as useful approaches exploited by L.pneumophila to modify host proteins.Some effectors catalyze the addition of host protein PTMs,while others mediate the removal of PTMs from host proteins.In this review,we summarize L.pneumophila effector-mediated PTMs of host proteins,including phosphorylation,ubiquitination,glycosylation,AMPylation,phosphocholination,methylation,and ADP-ribosylation,as well as dephosphorylation,deubiquitination,deAMPylation,deADP-ribosylation,dephosphocholination,and delipidation.We describe their molecular mechanisms and biological functions in the regulation of bacterial growth and Legionella-containing vacuole biosynthesis and in the disruption of host immune and defense machinery.
