Summary In Arabidopsis, both the membrane-anchored receptor-like kinase （RLK） BAK1 and the receptor-like cytoplasmic kinase （RLCK） BIK1 are important mediators of transmembrane signal transduction that regulate pl...Summary In Arabidopsis, both the membrane-anchored receptor-like kinase （RLK） BAK1 and the receptor-like cytoplasmic kinase （RLCK） BIK1 are important mediators of transmembrane signal transduction that regulate plant development and immunity. However, little attention has been paid to their genetic association. This study found the bak1 bik1 double mutant of Arabidopsis displayed a severe dwarfism phenotype due to constitutive immunity and cell death in developing plants. These data suggest that BIK1 cooperates with BAK1 to regulate constitutive immunity and cell death.展开更多
Arabidopsis BOTRYTIS-INDUCED KINASE1(BIK1)is a receptor-like cytoplasmic kinase acting early in multiple signaling pathways important for plant growth and innate immunity.It is known to form a signaling complex with a...Arabidopsis BOTRYTIS-INDUCED KINASE1(BIK1)is a receptor-like cytoplasmic kinase acting early in multiple signaling pathways important for plant growth and innate immunity.It is known to form a signaling complex with a cell-surface receptor FLS2 and a co-receptor kinase BAK1 to transduce signals upon perception of pathogen-asso-ciated molecular patterns(PAMPs).Although site-specifi c phosphorylation is speculated to mediate the activation and function of BIK1,few studies have been devoted to complete profiling of BIK1 phosphorylation residues.Here,we identified nineteen in vitro autophosphoryla-tion sites of BIK1 including three phosphotyrosine sites,thereby proving BIK1 is a dual-specifi city kinase for the fi rst time.The kinase activity of BIK1 substitution mutants were explicitly assessed using quantitative mass spec-trometry(MS).Thr-237,Thr-242 and Tyr-250 were found to most signifi cantly affect BIK1 activity in autophosphoryla-tion and phosphorylation of BAK1 in vitro.A structural model of BIK1 was built to further illustrate the molecular functions of specifi c phosphorylation residues.We also mapped new sites of FLS2 phosphorylation by BIK1,which are different from those by BAK1.These in vitro results could provide new hypotheses for more in-depth in vivo studies leading to deeper understanding of how phosphorylation contributes to BIK1 activation and medi-ates downstream signaling specifi city.展开更多
Receptor-like kinases(RLKs) play important roles in plant immunity signaling; thus, many are hijacked by pathogen effectors to promote successful pathogenesis. Xanthomonas oryzae pv. oryzae(Xoo) is the causal agent of...Receptor-like kinases(RLKs) play important roles in plant immunity signaling; thus, many are hijacked by pathogen effectors to promote successful pathogenesis. Xanthomonas oryzae pv. oryzae(Xoo) is the causal agent of rice leaf blight disease. The strain PXO99 A has 18 non-TAL(transcription activation-like) effectors; however, their mechanisms of action and host target proteins remain largely unknown. Although the effector XopR from the Xoo strain MAFF311018 was shown to suppress PAMP-triggered immune responses in Arabidopsis, its target has not yet been identified. Here, we show that PXO99 A XopR interacts with BIK1 at the plasma membrane. BIK1 is a receptor-like cytoplasmic kinase(RLCK) belonging to the RLK family of proteins and mediates PAMP-triggered stomatal immunity. In turn, BIK1 phosphorylates XopR. Furthermore, XopR suppresses PAMP-triggered stomatal closure in transgenic Arabidopsis expressing XopR. In addition, XopR is able to associate with RLCKs other than BIK1. These results suggest that XopR likely suppresses plant immunity by targeting BIK1 and other RLCKs.展开更多
基金supported by the National Natural Science Foundation of China(31571249 and 31425003)
文摘Summary In Arabidopsis, both the membrane-anchored receptor-like kinase （RLK） BAK1 and the receptor-like cytoplasmic kinase （RLCK） BIK1 are important mediators of transmembrane signal transduction that regulate plant development and immunity. However, little attention has been paid to their genetic association. This study found the bak1 bik1 double mutant of Arabidopsis displayed a severe dwarfism phenotype due to constitutive immunity and cell death in developing plants. These data suggest that BIK1 cooperates with BAK1 to regulate constitutive immunity and cell death.
基金the National Natural Science Foundation of China(Grant Nos.31170782 and 31100208)Tianjin Natural Science Foundation(Grant No.11JCYBJC25500)Spe-cialized Research Fund for the Doctoral Program of Higher Education(Grant No.20110031120019).
文摘Arabidopsis BOTRYTIS-INDUCED KINASE1(BIK1)is a receptor-like cytoplasmic kinase acting early in multiple signaling pathways important for plant growth and innate immunity.It is known to form a signaling complex with a cell-surface receptor FLS2 and a co-receptor kinase BAK1 to transduce signals upon perception of pathogen-asso-ciated molecular patterns(PAMPs).Although site-specifi c phosphorylation is speculated to mediate the activation and function of BIK1,few studies have been devoted to complete profiling of BIK1 phosphorylation residues.Here,we identified nineteen in vitro autophosphoryla-tion sites of BIK1 including three phosphotyrosine sites,thereby proving BIK1 is a dual-specifi city kinase for the fi rst time.The kinase activity of BIK1 substitution mutants were explicitly assessed using quantitative mass spec-trometry(MS).Thr-237,Thr-242 and Tyr-250 were found to most signifi cantly affect BIK1 activity in autophosphoryla-tion and phosphorylation of BAK1 in vitro.A structural model of BIK1 was built to further illustrate the molecular functions of specifi c phosphorylation residues.We also mapped new sites of FLS2 phosphorylation by BIK1,which are different from those by BAK1.These in vitro results could provide new hypotheses for more in-depth in vivo studies leading to deeper understanding of how phosphorylation contributes to BIK1 activation and medi-ates downstream signaling specifi city.
基金supported by the National Natural Science Foundation of China(31322009)the National Basic Research Program of China(2015CB910200)the State Key Laboratory of Plant Genomics of China(SKLPG2011B0301,SKLPG2011A0301)
文摘Receptor-like kinases(RLKs) play important roles in plant immunity signaling; thus, many are hijacked by pathogen effectors to promote successful pathogenesis. Xanthomonas oryzae pv. oryzae(Xoo) is the causal agent of rice leaf blight disease. The strain PXO99 A has 18 non-TAL(transcription activation-like) effectors; however, their mechanisms of action and host target proteins remain largely unknown. Although the effector XopR from the Xoo strain MAFF311018 was shown to suppress PAMP-triggered immune responses in Arabidopsis, its target has not yet been identified. Here, we show that PXO99 A XopR interacts with BIK1 at the plasma membrane. BIK1 is a receptor-like cytoplasmic kinase(RLCK) belonging to the RLK family of proteins and mediates PAMP-triggered stomatal immunity. In turn, BIK1 phosphorylates XopR. Furthermore, XopR suppresses PAMP-triggered stomatal closure in transgenic Arabidopsis expressing XopR. In addition, XopR is able to associate with RLCKs other than BIK1. These results suggest that XopR likely suppresses plant immunity by targeting BIK1 and other RLCKs.
