Determination of v-Mos-Catalyzed Phosphorylation Sites and Autophosphorylation Sites on MAP Kinase Kinase by ESI/MS

Resing, Katheryn A.; Mansour, Sam J.; Hermann, April S.; Johnson, Richard S.; Candia, Julian M.; Fukasawa, Kenji; Woude, George F. Vande; Ahn, Natalie G.

doi:10.1021/bi00008a027

Cited by 77 publications

(65 citation statements)

References 32 publications

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“…Notably, we did not detect any phospho-Tyr from the AtMEK1 autophosphorylation reaction. This autophosphorylation property is different from that of animal MEKs, which autophosphorylate on Ser, Thr, and Tyr residues (Crews and Erikson, 1992;Seger et al, 1992;Resing et al, 1995). ATMPK4 autophosphorylated predominately on Tyr; small amounts of phospho-Ser were also detected (Fig.…”

Section: Activation Of Atmpk4 Is Accompanied By Thr and Tyr Phosphorymentioning

confidence: 83%

ATMPK4, an Arabidopsis Homolog of Mitogen-Activated Protein Kinase, Is Activated in Vitro by AtMEK1 through Threonine Phosphorylation

et al. 2000

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The modulation of mitogen-activated protein kinase (MAPK) activity regulates many intracellular signaling processes. In animal and yeast cells, MAP kinases are activated via phosphorylation by the dual-specificity kinase MEK (MAP kinase kinase). Several plant homologs of MEK and MAPK have been identified, but the biochemical events underlying the activation of plant MAPKs remain unknown. We describe the in vitro activation of an Arabidopsis homolog of MAP kinase, ATMPK4. ATMPK4 was phosphorylated in vitro by an Arabidopsis MEK homolog, AtMEK1. This phosphorylation occurred principally on threonine (Thr) residues and resulted in elevated ATMPK4 kinase activity. A second Arabidopsis MEK isoform, ATMAP2K␣, failed to phosphorylate ATMPK4 in vitro. Tyr dephosphorylation by the Arabidopsis Tyr-specific phosphatase AtPTP1 resulted in an almost complete loss of ATMPK4 activity. Immunoprecipitates of Arabidopsis extracts with anti-ATMPK4 antibodies displayed myelin basic protein kinase activity that was sensitive to treatment with AtPTP1. These results demonstrate that a plant MEK can phosphorylate and activate MAPK, and that Tyr phosphorylation is critical for the catalytic activity of MAPK in plants. Surprisingly, in contrast to the animal enzymes, AtMEK1 may not be a dual-specificity kinase but, rather, the required Tyr phosphorylation on ATMPK4 may result from autophosphorylation.

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Section: Activation Of Atmpk4 Is Accompanied By Thr and Tyr Phosphorymentioning

confidence: 83%

ATMPK4, an Arabidopsis Homolog of Mitogen-Activated Protein Kinase, Is Activated in Vitro by AtMEK1 through Threonine Phosphorylation

et al. 2000

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“…MKK1 Activation Requires Regulatory Serine Phosphorylation Sites-MKK1 is activated by phosphorylation at Ser-218 and Ser-222 (29,30). The dependence of MKK1 activation by MKP-1 on these phosphorylation sites was examined by coexpressing MKP-1 with a series of MKK1 mutants with varying specific activities.…”

Section: Mkp-1 Expressionmentioning

confidence: 99%

Feedback Regulation of Raf-1 and Mitogen-activated Protein Kinase (MAP) Kinase Kinases 1 and 2 by MAP Kinase Phosphatase-1 (MKP-1)

Shapiro¹,

Ahn²

1998

Journal of Biological Chemistry

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Inactivation of growth factor-regulated mitogen-activated protein (MAP) kinases (ERK1 and ERK2) has been proposed to occur in part through dephosphorylation by the dual specificity MAP kinase phosphatase-1 (MKP-1), an immediate early gene that is induced by mitogenic signaling. In this study, we examined the effect of MKP-1 on signaling components upstream of ERK1 and ERK2. Coexpression of MKK1 or MKK2 with MKP-1 resulted in 7-10-fold activation of mitogen-activated protein kinase kinase (MKK), which required the presence of regulatory serine phosphorylation sites. Endogenous MKK1 and MKK2 were also activated upon MKP-1 expression. Raf-1, a direct regulator of MKK1 and MKK2, was activated under these conditions, and a synergistic activation of MKK was observed upon coexpression of Raf-1 and MKP-1. This effect did not appear to involve synthesis of autocrine growth factors or the inhibition of basal extracellular signal-regulated kinase (ERK) activity but was inhibited by a dominant negative Ras mutant, indicating that MKP-1 enhances Ras-dependent activation of Raf-1 in a cell autonomous manner. This study demonstrates positive feedback regulation of Raf-1 and MKK by the MKP-1 immediate early gene and a potential mechanism for activating Raf-1/MKK signaling pathways alternative to those involving ERK. The mitogen-activated protein (MAP)1 kinase cascade has emerged as a key signaling pathway regulating factor-dependent cell growth and differentiation through intracellular phosphorylation (1, 2). Growth factor regulation of this pathway involves the phosphorylation and activation of MAP kinases, ERK1 and ERK2, by MAP kinase kinases, MKK1 and MKK2 (3-6). ERKs 1 and 2 phosphorylate various targets including upstream and downstream protein kinases, cell surface receptors, and nuclear transcription factors (1, 7). MKKs 1 and 2, in turn, can be activated through phosphorylation by members of the Raf protein kinase family, including Raf-1, which is ubiquitously expressed (8, 9). Receptor-dependent activation of Raf-1 involves its interaction with p21 Ras, through a mechanism that is not completely defined, but appears to involve Raf-1 dimerization and phosphorylation by heterologous protein kinases (10 -13).The product of the immediate early gene, MAP kinase phosphatase (MKP-1), is able to dephosphorylate phosphoserine/ threonine as well as phosphotyrosine residues, and shows selectivity for ERKs 1 and 2 in vitro, with lower activity toward other MAP kinases such as JNK and p38 MAP kinase (14, 15). MKP-1 inactivates ERK following growth factor stimulation in intact cells and also suppresses signaling downstream of ERK at the level of gene transcription and proliferation (15-17), most likely through its inhibitory effects on MAP kinase. Interestingly, MKP-1 is transcriptionally induced by stress-regulated pathways such as those occurring in response to UV treatment or activation of stress-regulated protein kinases (18,19), suggesting that MKP-1 may function as a mediator of cross-regulatory pathways between mammalian prot...

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“…Mos phosphorylates and activates MAPK kinase (MEK), which in turn phosphorylates and activates MAPK (Nebreda and Hunt 1993;Posada et al 1993;Shibuya and Ruderman 1993;Pham et al 1995;Resing et al 1995;Huang and Ferrell 1996; for review, see Kosako et al 1994). We proposed that Mos could be involved in generating the gap phases in the first mitotic cell cycle (Murakami and Vande Woude 1998) because Mos protein is degraded 20-30 min after fertilization (Watanabe et al 1991).…”

mentioning

confidence: 99%

Mos positively regulates Xe-Wee1 to lengthen the first mitotic cell cycle of Xenopus

Murakami¹,

Copeland²,

Woude³

1999

Genes & Development

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Several key developmental events occur in the first mitotic cell cycle of Xenopus; consequently this cycle has two gap phases and is ∼60-75 min in length. In contrast, embryonic cycles 2-12 consist only of S and M phases and are 30 min in length. Xe-Wee1 and Mos are translated and degraded in a developmentally regulated manner. Significantly, both proteins are present in the first cell cycle. We showed previously that the expression of nondegradable Mos, during early interphase, delays the onset of M phase in the early embryonic cell cycles. Here we report that Xe-Wee1 is required for the Mos-mediated M-phase delay. We find that Xe-Wee1 tyrosine autophosphorylation positively regulates Xe-Wee1 and is only detected in the first 30 min of the first cell cycle. The level and duration of Xe-Wee1 tyrosine phosphorylation is elevated significantly when the first cell cycle is elongated with nondegradable Mos. Importantly, we show that the tyrosine phosphorylation of Xe-Wee1 is required for the Mos-mediated M-phase delay. These findings indicate that Mos positively regulates Xe-Wee1 to generate the G 2 phase in the first cell cycle and establish a direct link between the MAPK signal transduction pathway and Wee1 in vertebrates.[Key Words: Mos; Xe-Wee1; Xenopus; embryonic cell cycle]Received December 22, 1998; revised version accepted January 15, 1999.The oocytes, eggs, and embryos of Xenopus undergo an extraordinary series of cell-cycle transitions that are critical for the propagation and development of the organism (Gerhart 1980;. In oocytes, the meiotic cell cycle is initiated in response to progesterone and consists of two consecutive M phases without an intervening S phase. The resultant eggs are arrested at metaphase of meiosis II until fertilization, which releases the arrest and initiates the series of mitotic cycles. The first mitotic cell cycle following fertilization is ∼60-75 min long and has two gap phases. In contrast, mitotic cycles 2-12 are ∼25-30 minutes long and consist only of alternating S and M phases. The gap phases in the first cycle are necessary to accommodate the completion of meiosis II, the fusion of the sperm and egg pro-nuclei and the cortical rotation that determines the second axis of asymmetry (Gerhart 1980;. The early embryonic cell cycles proceed in the absence of growth and transcription, therefore the gap phases in the first cycle are unlike those found in somatic cell cycles (Gerhart 1980;Newport and Kirschner 1982). We have studied the mechanism that regulates the length of the first mitotic cell cycle and propose that the G 2 phase in this cycle is generated by the developmentally regulated translation of Xe-Wee1 and degradation of Mos.The cyclin B/cdc2 complex regulates the entry into M phase (for review, see Norbury and Nurse 1992; Morgan 1997). The Wee1 and Myt1 protein kinases inhibit entry into M phase by mediating the phosphorylation of cdc2 on two inhibitory sites, T14 and Y15. Wee1 is localized to the nucleus and phosphorylates only the Y15 residue, whereas Myt 1 is local...

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Determination of v-Mos-Catalyzed Phosphorylation Sites and Autophosphorylation Sites on MAP Kinase Kinase by ESI/MS

Cited by 77 publications

References 32 publications

ATMPK4, an Arabidopsis Homolog of Mitogen-Activated Protein Kinase, Is Activated in Vitro by AtMEK1 through Threonine Phosphorylation

ATMPK4, an Arabidopsis Homolog of Mitogen-Activated Protein Kinase, Is Activated in Vitro by AtMEK1 through Threonine Phosphorylation

Feedback Regulation of Raf-1 and Mitogen-activated Protein Kinase (MAP) Kinase Kinases 1 and 2 by MAP Kinase Phosphatase-1 (MKP-1)

Mos positively regulates Xe-Wee1 to lengthen the first mitotic cell cycle of Xenopus

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