OMTK1, a Novel MAPKKK, Channels Oxidative Stress Signaling through Direct MAPK Interaction

Nakagami, Hirofumi; Kiegerl, Stefan; Hirt, Heribert

doi:10.1074/jbc.m312662200

Cited by 140 publications

(92 citation statements)

References 29 publications

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“…Evidence for activation of MAPKs by ROS has been provided by several studies in different plant species (Kovtun et al, 2000;Desikan et al, 2001;Yuasa et al, 2001;Nakagami et al, 2004;Rentel et al, 2004). A possible explanation for the different kinetics of MAPK activation by copper and cadmium ions might therefore stem from the different cellular reaction mechanisms of these two metals.…”

Section: Discussionmentioning

confidence: 99%

“…Cloning of HA-tagged SIMK, MMK2, MMK3, and SAMK and myc-tagged SIMKK into the plant expression vector pRT101 was reported in Kiegerl et al (2000), Cardinale et al (2002), and Nakagami et al (2004). The open reading frames of MEK1 and PRKK were fused at their C termini to a double myc epitope and cloned into the vector pRT101.…”

Section: Transient Expression Assaysmentioning

confidence: 99%

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Heavy Metal Stress. Activation of Distinct Mitogen-Activated Protein Kinase Pathways by Copper and Cadmium

2004

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Excessive amounts of heavy metals adversely affect plant growth and development. Whereas some regions naturally contain high levels of heavy metals, anthropogenic release of heavy metals into the environment continuously increases soil contamination. The presence of elevated levels of heavy metal ions triggers a wide range of cellular responses including changes in gene expression and synthesis of metal-detoxifying peptides. To elucidate signal transduction events leading to the cellular response to heavy metal stress we analyzed protein phosphorylation induced by elevated levels of copper and cadmium ions as examples for heavy metals with different physiochemical properties and functions. Exposure of alfalfa (Medicago sativa) seedlings to excess copper or cadmium ions activated four distinct mitogen-activated protein kinases (MAPKs): SIMK, MMK2, MMK3, and SAMK. Comparison of the kinetics of MAPK activation revealed that SIMK, MMK2, MMK3, and SAMK are very rapidly activated by copper ions, while cadmium ions induced delayed MAPK activation. In protoplasts, the MAPK kinase SIMKK specifically mediated activation of SIMK and SAMK but not of MMK2 and MMK3. Moreover, SIMKK only conveyed MAPK activation by CuCl 2 but not by CdCl 2 . These results suggest that plants respond to heavy metal stress by induction of several distinct MAPK pathways and that excess amounts of copper and cadmium ions induce different cellular signaling mechanisms in roots.Heavy metal ions play essential roles in many physiological processes. In trace amounts, several of these ions are required for metabolism, growth, and development. However, problems arise when cells are confronted with an excess of these vital ions or with nonnutritional ions that lead to cellular damage (Avery, 2001;Schü tzendü bel and Polle, 2002;Gaetke and Chow, 2003;Polle and Schü tzendü bel, 2003). Heavy metal toxicity comprises inactivation of biomolecules by either blocking essential functional groups or by displacement of essential metal ions (Goyer, 1997). In addition, autoxidation of redox-active heavy metals and production of reactive oxygen species (ROS) by the Fenton reaction causes cellular injury (Stohs and Bagchi, 1995).In response to toxic levels of heavy metals, plants synthesize Cys-rich, metal-binding peptides including phytochelatins and metallothioneins. Therefore, heavy metals can be detoxified by chelation and sequestration in the vacuole (Clemens, 2001;Cobbett and Goldsbrough, 2002), and various membrane transport systems play an important role in metal ion homeostasis and tolerance (Hall and Williams, 2003).Gene expression patterns change when plants encounter excessive amounts of heavy metals.Cadmium-and copper-responsive genes have been shown to code for signal transduction components, such as the Arabidopsis mitogen-activated protein kinase kinase kinase (MAPKKK) MEKK1, transcription factors, stress-induced proteins, proteins participating in protein folding, and sulfur and glutathione metabolism (Xiang and Oliver, 1998;Suzuki et al., 2001;Louie ...

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Section: Discussionmentioning

confidence: 99%

Section: Transient Expression Assaysmentioning

confidence: 99%

Heavy Metal Stress. Activation of Distinct Mitogen-Activated Protein Kinase Pathways by Copper and Cadmium

2004

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“…H 2 O 2 is a relatively stable and mobile signaling molecule that can transmit through the vasculature (46). Similar to OMTK1, a MEKK1 ortholog in alfalfa, MEKK1 is stabilized and activated upon H 2 O 2 treatment (47). 6 In the absence of MEKK1, particular cell types, such as cells in the vasculature, may become less sensitive to H 2 O 2 and result in H 2 O 2 accumulation and cell death.…”

Section: Discussionmentioning

confidence: 99%

MEKK1 Is Required for MPK4 Activation and Regulates Tissue-specific and Temperature-dependent Cell Death in Arabidopsis

Ichimura

Casais

Peck

et al. 2006

Journal of Biological Chemistry

275

278

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Innate immunity signaling pathways in both animals and plants are regulated by mitogen-activated protein kinase (MAPK) cascades. An Arabidopsis MAPK cascade (MEKK1, MKK4/MKK5, and MPK3/MPK6) has been proposed to function downstream of the flagellin receptor FLS2 based on biochemical assays using transient overexpression of candidate components. To genetically test this model, we characterized two mekk1 mutants. We show here that MEKK1 is not required for flagellin-triggered activation of MPK3 and MPK6. Instead, MEKK1 is essential for activation of MPK4, a MAPK that negatively regulates systemic acquired resistance. We also showed that MEKK1 negatively regulates temperature-sensitive and tissue-specific cell death and H 2 O 2 accumulation that are partly dependent on both RAR1, a key component in resistance protein function, and SID2, an isochorismate synthase required for salicylic acid production upon pathogen infection.

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“…Looking for analogous scaffolding proteins in plants revealed the presence of some MAP kinases that play dual roles as scaffold protein and kinase enzyme at the same time. For example, the MAPKKK OMTK1 (oxidative stress-activated MAP triple kinase 1), which belongs to the alfalfa MAPKKK family, plays a role as an adapter and a phosphate transporter at the same time (Nakagami et al 2004). Other studies report that MAP kinases would act as structural adaptors and enzymatic activators in yeast (Edmunds and Mahadevan 2004).…”

Section: Map Kinase Complexity In Environmental Stresses' Signalingmentioning

confidence: 99%

MAPK cascades and major abiotic stresses

et al. 2014

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Plants have evolved with complex signaling circuits that operate under multiple conditions and govern numerous cellular functions. Stress signaling in plant cells is a sophisticated network composed of interacting proteins organized into tiered cascades where the function of a molecule is dependent on the interaction and the activation of another. In a linear scheme, the receptors of cell surface sense the stimuli and convey stress signals through specific pathways and downstream phosphorylation events controlled by mitogen-activated protein (MAP) kinases and second messengers, leading to appropriate adaptive responses. The specificity of the pathway is guided by scaffolding proteins and docking domains inside the interacting partners with distinctive structures and functions. The flexibility and the fine-tuned organization of the signaling molecules drive the activated MAP kinases into the appropriate location and connection to control and integrate the information flow. Here, we overview recent findings of the involvement of MAP kinases in major abiotic stresses (drought, cold and temperature fluctuations) and we shed light on the complexity and the specificity of MAP kinase signaling modules.

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OMTK1, a Novel MAPKKK, Channels Oxidative Stress Signaling through Direct MAPK Interaction

Cited by 140 publications

References 29 publications

Heavy Metal Stress. Activation of Distinct Mitogen-Activated Protein Kinase Pathways by Copper and Cadmium

Heavy Metal Stress. Activation of Distinct Mitogen-Activated Protein Kinase Pathways by Copper and Cadmium

MEKK1 Is Required for MPK4 Activation and Regulates Tissue-specific and Temperature-dependent Cell Death in Arabidopsis

MAPK cascades and major abiotic stresses

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