Analysis of Phosphorylation of the BRI1/BAK1 Complex in Arabidopsis Reveals Amino Acid Residues Critical for Receptor Formation and Activation of BR Signaling

Yun, Hye Sup; Bae, Young Hee; Lee, Yun Ji; Chang, Soo Chul; Kim, Seong Ki; Li, Jianming; Nam, Kee‐Hyun

doi:10.1007/s10059-009-0023-1

Cited by 50 publications

(48 citation statements)

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“…The extracellular domains of BRI1 and BAK1 also affect the stable association of the two proteins. The substitution of glutamic acid for leucine (L32E, L46E) in the leucine zipper domain of BAK1 resulted in the reduced binding of BAK1 to BRI1 (Yun et al, 2009). In contrast, the substitution of asparagine for aspartic acid (D122N) in the third LRR of elg mutation resulted in a gain-of-function mutation in BAK1 and the mutant BAK1 exhibited higher affinity for BRI1, even in the presence of low concentrations of BR (Jaillais et al, 2011a;Whippo and Hangarter, 2005).…”

Section: Identification Of Bak1 In Br Signalingmentioning

confidence: 99%

Assessing the Diverse Functions of BAK1 and Its Homologs in Arabidopsis, beyond BR Signaling and PTI Responses

Kim

Nam

2013

Molecules and Cells

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Plants possess a variety of extracellular leucine-rich repeats receptor-like kinases (LRR-RLKs) to coordinate developmental programs with responses to environmental changes. Out of sixteen families of LRR-RLKs in Arabidopsis, the LRR-RLKII family consists of fourteen individual members, including five Arabidopsis thaliana somatic embryogenesis receptor kinases (AtSERKs). BAK1/AtSERK3 was first identified as a dual co-receptor of BRI1 and FLS2, mediating BR signaling and pathogen-associated molecular pattern (PAMP) triggered immunity (PTI), respectively. Since its identification, many researchers have attempted to elucidate the phosphorylation mechanisms between receptor complexes and identify additional components that interact with receptor complexes to transduce the signaling downstream. Relatively detailed early events in complex formation, phosphorylation sites on the BRI1/BAK1 complex and BAK1-interacting proteins, such as BIK1 and PUB13, have been identified. Small receptor complexes consisting of BAK1 and BIR1 or BAK1 and AtSERK4 regulate cell death during steady state conditions. Moreover, the redundant and distinct functions of AtSERK proteins and other members of the LRR-RLKII family have been revealed. This review focuses on the integration of the information from the most recent studies concerning BAK1 and its homologs.

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Section: Identification Of Bak1 In Br Signalingmentioning

confidence: 99%

Assessing the Diverse Functions of BAK1 and Its Homologs in Arabidopsis, beyond BR Signaling and PTI Responses

Kim

Nam

2013

Molecules and Cells

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“…Coupled with more recent biochemical approaches, these studies have provided fascinating insights into the various aspects of plant steroid signaling, ranging from BR perception at the cell surface to activation of transcription factors in the nucleus (Kim and Wang, 2010). According to current concepts, BRs directly bind to the extracellular domain of the receptor-like kinase BRASSINOSTEROID INSENSI-TIVE1 (BRI1; She et al, 2011), thereby inducing a series of biochemical responses, including heterodimerization of BRI1 with, and activation of, another receptor kinase, BRI1-ASSOCIATED KINASE1 (BAK1; Li et al, 2002;Yun et al, 2009), phosphorylation of BRI1-interacting signaling kinases (Tang et al, 2008), and activation of the protein phosphatase BRI1 SUPPRESSOR PROTEIN1 . These events eventually culminate in inhibition of the shaggy-like kinase BRI1-INSENSITIVE2 (Vert and Chory, 2006) and resultant activation of the transcription factors BRASSINAZOLE-RESISTANT1 (BZR1) and BRI1-EMS-SUPPRESSOR1 (BES1)/BZR2 that orchestrate downstream gene expression (Sun et al, 2010;Yu et al, 2011).…”

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Brassinosteroids Antagonize Gibberellin- and Salicylate-Mediated Root Immunity in Rice

et al. 2012

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Brassinosteroids (BRs) are a unique class of plant steroid hormones that orchestrate myriad growth and developmental processes. Although BRs have long been known to protect plants from a suite of biotic and abiotic stresses, our understanding of the underlying molecular mechanisms is still rudimentary. Aiming to further decipher the molecular logic of BR-modulated immunity, we have examined the dynamics and impact of BRs during infection of rice (Oryza sativa) with the root oomycete Pythium graminicola. Challenging the prevailing view that BRs positively regulate plant innate immunity, we show that P. graminicola exploits BRs as virulence factors and hijacks the rice BR machinery to inflict disease. Moreover, we demonstrate that this immunesuppressive effect of BRs is due, at least in part, to negative cross talk with salicylic acid (SA) and gibberellic acid (GA) pathways. BR-mediated suppression of SA defenses occurred downstream of SA biosynthesis, but upstream of the master defense regulators NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 and OsWRKY45. In contrast, BR alleviated GA-directed immune responses by interfering at multiple levels with GA metabolism, resulting in indirect stabilization of the DELLA protein and central GA repressor SLENDER RICE1 (SLR1). Collectively, these data favor a model whereby P. graminicola coopts the plant BR pathway as a decoy to antagonize effectual SA-and GA-mediated defenses. Our results highlight the importance of BRs in modulating plant immunity and uncover pathogen-mediated manipulation of plant steroid homeostasis as a core virulence strategy.

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Section: Bri1-associated Receptor Kinase 1 (Bak1)mentioning

confidence: 99%

“…BAK1 also has a critical phosphorylation site for its catalytic activity. L46 seems to be involved in the binding of BAK1 to BRI1 since its point mutation to glutamate abolished BAK1 binding to BRI1 in yeast [72].There are six phosphorylation sites in the intracellular region of BAK1. T445, T446, T449, and T450 are in the activation loop and S290 and T312 are in the CT domain [28,62].…”

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Update on Phosphorylation-Mediated Brassinosteroid Signaling Pathways

Lee¹,

Kim

2012

Journal of Life Science

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Protein phosphorylation is a universal mechanism that regulates cellular activities. The brassinosteroid (BR) signal transduction pathway is a relay of phosphorylation and dephosphorylation cascades. It starts with the BR-induced activation of the membrane receptor kinase brassinosteroid insensitive 1 (BRI1), resulting in the dephosphorylation of transcription factors such as BZR1/BES2 and BZR2/BES1 followed by BR-induced gene expression. Brassinosteroid signal transduction research has progressed rapidly by identifying the phosphorylation/dephosphorylation site(s) of the BR-regulated kinase and phosphatase substrates with a simultaneous pursuit of mutant phenotypes. Autophosphorylation, transphosphorylation, and serine/threonine and tyrosine phosphorylation of the receptor protein kinases BRI1 and BRI1-associated kinase (BAK1) have increased the understanding of the regulatory role of those kinases during physiological and developmental processes in plants. The phosphorylation event initiated by BR is also found in the regulation of receptor-mediated endocytosis and the subsequent degradation of the receptor. However, the basic molecular links of the BR signal transduction pathway are not well understood regarding this phosphorylation/dephosphorylation event. This review summarizes the current state of BR signal transduction research to uncover the phosphorylation/dephosphorylation networks and suggests directions for future research on steroid signal transduction to gain a more comprehensive understanding of the process. IntroductionBrassinosteroids are the only group of steroid hormones discovered in plants, which are different from steroid hormones in the animal system that has several different steroid hormones. Brassinosteroids regulate plant growth and development such as cell elongation, vascular development, senescence, stress responses, and photomorphogenesis [10,11,68]. BR-related mutants of the brassinosteroid biosynthesis pathway and signal transduction exhibited a short hypocotyl, opened cotyledons, and de-etiolation in the dark. Under light conditions, they exhibited severe dwarfism, aggregated and dark-green rosette leaves with epinasty, decreased elongation of the petiole, defects in the fertility of pollens, apical dominance, and senescence [9,69]. Therefore, brassinosteroids have pivotal roles in plant growth and differentiation [11,18]. In animal systems, steroid ligands bind to nuclear binding receptors that act as transcriptional regulators [65]. However, in plant systems, BRs bind to BRI1, an LRR-RLK on the plasma membrane, and this binding induces a signal, which is transduced to the nucleus through several signaling components in the cytoplasm [33,63].For the past few years, information on brassinosteroid-mediated phosphorylation has increased enormously. Not only serine/threonine phosphorylation but also tyrosine phosphorylation have been found, and the significance of autophosphorylation and transphosphorylation became known. Recently, many phosphorylation sites on protein kinases in ...

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Analysis of Phosphorylation of the BRI1/BAK1 Complex in Arabidopsis Reveals Amino Acid Residues Critical for Receptor Formation and Activation of BR Signaling

Cited by 50 publications

References 42 publications

Assessing the Diverse Functions of BAK1 and Its Homologs in Arabidopsis, beyond BR Signaling and PTI Responses

Assessing the Diverse Functions of BAK1 and Its Homologs in Arabidopsis, beyond BR Signaling and PTI Responses

Brassinosteroids Antagonize Gibberellin- and Salicylate-Mediated Root Immunity in Rice

Update on Phosphorylation-Mediated Brassinosteroid Signaling Pathways

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