scholarly journals Mitogen-activated protein kinase 6 negatively regulates secondary wall biosynthesis by modulating MYB46 protein stability in Arabidopsis thaliana

PLoS Genetics ◽  
2021 ◽  
Vol 17 (4) ◽  
pp. e1009510
Author(s):  
Jong Hee Im ◽  
Jae-Heung Ko ◽  
Won-Chan Kim ◽  
Brent Crain ◽  
Daniel Keathley ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Translational Regulation ◽  
Secondary Wall ◽  
Secondary Cell Wall ◽  
Specific Activity ◽  
Mitogen Activated Protein Kinase ◽  
Myb Transcription Factor ◽  
In Planta ◽  
Mitogen Activated Protein

The R2R3-MYB transcription factor MYB46 functions as a master switch for secondary cell wall biosynthesis, ensuring the exquisite expression of the secondary wall biosynthetic genes in the tissues where secondary walls are critical for growth and development. At the same time, suppression of its function is needed when/where formation of secondary walls is not desirable. Little is known about how this opposing control of secondary cell wall formation is achieved. We used both transient and transgenic expression of MYB46 and mitogen-activated protein kinase 6 (MPK6) to investigate the molecular mechanism of the post-translational regulation of MYB46. We show that MYB46 is phosphorylated by MPK6, leading to site specific phosphorylation-dependent degradation of MYB46 by the ubiquitin-mediated proteasome pathway. In addition, the MPK6-mediated MYB46 phosphorylation was found to regulate in planta secondary wall forming function of MYB46. Furthermore, we provide experimental evidences that MYB83, a paralog of MYB46, is not regulated by MPK6. The coupling of MPK signaling to MYB46 function provides insights into the tissue- and/or condition-specific activity of MYB46 for secondary wall biosynthesis.

scholarly journals The Yeast Protein Kinase C Cell Integrity Pathway Mediates Tolerance to the Antifungal Drug Caspofungin through Activation of Slt2p Mitogen-Activated Protein Kinase Signaling

2003 ◽  
Vol 2 (6) ◽  
pp. 1200-1210 ◽  
Author(s):  
Cristina Reinoso-Martín ◽  
Christoph Schüller ◽  
Manuela Schuetzer-Muehlbauer ◽  
Karl Kuchler
Keyword(s):  
Cell Wall ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Antifungal Drug ◽  
Mitogen Activated Protein Kinase ◽  
Cell Integrity ◽  
Cell Wall Synthesis ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Yeast Genes

ABSTRACT The echinocandin caspofungin is a new antifungal drug that blocks cell wall synthesis through inhibition of β-(1-3)-glucan synthesis. Saccharomyces cerevisiae cells are able to tolerate rather high caspofungin concentrations, displaying high viability at low caspofungin doses. To identify yeast genes implicated in caspofungin tolerance, we performed a genome-wide microarray analysis. Strikingly, caspofungin treatment rapidly induces a set of genes from the protein kinase C (PKC) cell integrity signaling pathway, as well as those required for cell wall maintenance and architecture. The mitogen-activated protein kinase Slt2p is rapidly activated by phosphorylation, triggering signaling through the PKC pathway. Cells lacking genes such as SLT2, BCK1, and PKC1, as well as the caspofungin target gene, FKS1, display pronounced hypersensitivity, demonstrating that the PKC pathway is required for caspofungin tolerance. Notably, the cell surface integrity sensor Wsc1p, but not the sensors Wsc2-4p and Mid2p, is required for sensing caspofungin perturbations. The expression modulation of PKC target genes requires the transcription factor Rlm1p, which controls expression of several cell wall synthesis and maintenance genes. Thus, caspofungin-induced cell wall damage requires Wsc1p as a dedicated sensor to launch a protective response through the activated salvage pathway for de novo cell wall synthesis. Our results establish caspofungin as a specific activator of Slt2p stress signaling in baker's yeast.

scholarly journals Different polarisome components play distinct roles in Slt2p-regulated cortical ER inheritance in Saccharomyces cerevisiae

2013 ◽  
Vol 24 (19) ◽  
pp. 3145-3154 ◽  
Author(s):  
Xia Li ◽  
Susan Ferro-Novick ◽  
Peter Novick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Protein Kinase ◽  
Protein Phosphatase ◽  
Mitogen Activated Protein Kinase ◽  
Common Mechanism ◽  
Late Step ◽  
Mitogen Activated Protein ◽  
Cortical Endoplasmic Reticulum

Ptc1p, a type 2C protein phosphatase, is required for a late step in cortical endoplasmic reticulum (cER) inheritance in Saccharomyces cerevisiae. In ptc1Δ cells, ER tubules migrate from the mother cell and contact the bud tip, yet fail to spread around the bud cortex. This defect results from the failure to inactivate a bud tip–associated pool of the cell wall integrity mitogen-activated protein kinase, Slt2p. Here we report that the polarisome complex affects cER inheritance through its effects on Slt2p, with different components playing distinct roles: Spa2p and Pea2p are required for Slt2p retention at the bud tip, whereas Bni1p, Bud6p, and Sph1p affect the level of Slt2p activation. Depolymerization of actin relieves the ptc1Δ cER inheritance defect, suggesting that in this mutant the ER becomes trapped on the cytoskeleton. Loss of Sec3p also blocks ER inheritance, and, as in ptc1Δ cells, this block is accompanied by activation of Slt2p and is reversed by depolymerization of actin. Our results point to a common mechanism for the regulation of ER inheritance in which Slt2p activity at the bud tip controls the association of the ER with the actin-based cytoskeleton.

scholarly journals The fission yeast pmk1+ gene encodes a novel mitogen-activated protein kinase homolog which regulates cell integrity and functions coordinately with the protein kinase C pathway.

1996 ◽  
Vol 16 (12) ◽  
pp. 6752-6764 ◽  
Author(s):  
T Toda ◽  
S Dhut ◽  
G Superti-Furga ◽  
Y Gotoh ◽  
E Nishida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase C ◽  
Amino Acid ◽  
Protein Kinase ◽  
Fission Yeast ◽  
Mitogen Activated Protein Kinase ◽  
Cell Integrity ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Mapk Gene

We have isolated a gene, pmk1+, a third mitogen-activated protein kinase (MAPK) gene homolog from the fission yeast Schizosaccharomyces pombe. The predicted amino acid sequence shows the most homology (63 to 65% identity) to those of budding yeast Saccharomyces Mpk1 and Candida Mkc1. The Pmk1 protein contains phosphorylated tyrosines, and the level of tyrosine phosphorylation was increased in the dsp1 mutant which lacks an attenuating phosphatase for Pmk1. The level of tyrosine phosphorylation appears constant during hypotonic or heat shock treatment. The cells with pmk1 deleted (delta pmk1) are viable but show various defective phenotypes, including cell wall weakness, abnormal cell shape, a cytokinesis defect, and altered sensitivities to cations, such as hypersensitivity to potassium and resistance to sodium. Consistent with a high degree of conservation of amino acid sequence, multicopy plasmids containing the MPK1 gene rescued the defective phenotypes of the delta pmk1 mutant. The frog MAPK gene also suppressed the pmk1 disruptant. The results of genetic analysis indicated that Pmk1 lies on a novel MAPK pathway which does not overlap functionally with the other two MAPK pathways, the Spk1-dependent mating signal pathway and Sty1/Spc1/Phh1-dependent stress-sensing pathway. In Saccharomyces cerevisiae, Mpk1 is involved in cell wall integrity and functions downstream of the protein kinase C homolog. In contrast, in S. pombe, Pmk1 may not act in a linear manner with respect to fission yeast protein kinase C homologs. Interestingly, however, these two pathways are not independent; instead, they regulate cell integrity in a coordinate manner.

scholarly journals Transcriptional Coregulation by the Cell Integrity Mitogen-Activated Protein Kinase Slt2 and the Cell Cycle Regulator Swi4

2001 ◽  
Vol 21 (19) ◽  
pp. 6515-6528 ◽  
Author(s):  
Kristin Baetz ◽  
Jason Moffat ◽  
Jennifer Haynes ◽  
Michael Chang ◽  
Brenda Andrews
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Wall ◽  
Transcription Factor ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Regulatory Subunit ◽  
Cell Integrity ◽  
Mitogen Activated Protein

ABSTRACT In Saccharomyces cerevisiae, the heterodimeric transcription factor SBF (for SCB binding factor) is composed of Swi4 and Swi6 and activates gene expression at the G1/S-phase transition of the mitotic cell cycle. Cell cycle commitment is associated not only with major alterations in gene expression but also with highly polarized cell growth; the mitogen-activated protein kinase (MAPK) Slt2 is required to maintain cell wall integrity during periods of polarized growth and cell wall stress. We describe experiments aimed at defining the regulatory pathway involving the cell cycle transcription factor SBF and Slt2-MAPK. Gene expression assays and chromatin immunoprecipitation experiments revealed Slt2-dependent recruitment of SBF to the promoters of the G1 cyclinsPCL1 and PCL2 after activation of the Slt2-MAPK pathway. We performed DNA microarray analysis and identified other genes whose expression was reduced in both SLT2and SWI4 deletion strains. Genes that are sensitive to both Slt2 and Swi4 appear to be uniquely regulated and reveal a role for Swi4, the DNA-binding component of SBF, which is independent of the regulatory subunit Swi6. Some of the Swi4- and Slt2-dependent genes do not require Swi6 for either their expression or for Swi4 localization to their promoters. Consistent with these results, we found a direct interaction between Swi4 and Slt2. Our results establish a new Slt2-dependent mode of Swi4 regulation and suggest roles for Swi4 beyond its prominent role in controlling cell cycle transcription.

scholarly journals Mechanism of Mpk1 Mitogen-Activated Protein Kinase Binding to the Swi4 Transcription Factor and Its Regulation by a Novel Caffeine-Induced Phosphorylation

2009 ◽  
Vol 29 (24) ◽  
pp. 6449-6461 ◽  
Author(s):  
Andrew W. Truman ◽  
Ki-Young Kim ◽  
David E. Levin
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Protein Kinase ◽  
Dna Binding ◽  
Binding Site ◽  
Mutational Analysis ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Activation Mechanism ◽  
Mitogen Activated Protein

ABSTRACT The Mpk1 mitogen-activated protein kinase (MAPK) of the cell wall integrity signaling pathway uses a noncatalytic mechanism to activate the SBF (Swi4/Swi6) transcription factor. Active Mpk1 forms a complex with Swi4, the DNA-binding subunit of SBF, conferring the ability to bind DNA. Because SBF activation is independent of Mpk1 catalytic activity but requires Mpk1 to be in an active conformation, we sought to understand how Mpk1 interacts with Swi4. Mutational analysis revealed that binding and activation of Swi4 by Mpk1 requires an intact D-motif-binding site, a docking surface common to MAPKs that resides distal to the phosphorylation loop but does not require the substrate-binding site, revealing a novel mechanism for MAPK target regulation. Additionally, we found that Mpk1 binds near the autoinhibitory C terminus of Swi4, suggesting an activation mechanism in which Mpk1 substitutes for Swi6 in promoting Swi4 DNA binding. Finally, we show that caffeine is an atypical activator of cell wall integrity signaling, because it induces phosphorylation of the Mpk1 C-terminal extension at Ser423 and Ser428. These phosphorylations were dependent on the DNA damage checkpoint kinases, Mec1/Tel1 and Rad53. Phosphorylation of Ser423 specifically blocked SBF activation by preventing Mpk1 association with Swi4, revealing a novel mechanism for regulating MAPK target specificity.

scholarly journals Msb2 Signaling Mucin Controls Activation of Cek1 Mitogen-Activated Protein Kinase in Candida albicans

2009 ◽  
Vol 8 (8) ◽  
pp. 1235-1249 ◽  
Author(s):  
Elvira Román ◽  
Fabien Cottier ◽  
Joachim F. Ernst ◽  
Jesús Pla
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Protein Kinase ◽  
Osmotic Shock ◽  
Mitogen Activated Protein Kinase ◽  
Hog Pathway ◽  
High Osmolarity ◽  
Cell Wall Biogenesis ◽  
Solid Media ◽  
Mitogen Activated Protein

ABSTRACT We have characterized the role that the Msb2 protein plays in the fungal pathogen Candida albicans by the use of mutants defective in the putative upstream components of the HOG pathway. Msb2, in cooperation with Sho1, controls the activation of the Cek1 mitogen-activated protein kinase under conditions that damage the cell wall, thus defining Msb2 as a signaling element of this pathway in the fungus. msb2 mutants display altered sensitivity to Congo red, caspofungin, zymolyase, or tunicamycin, indicating that this protein is involved in cell wall biogenesis. Msb2 (as well as Sho1 and Hst7) is involved in the transmission of the signal toward Cek1 mediated by the Cdc42 GTPase, as revealed by the use of activated alleles (Cdc42G12V) of this protein. msb2 mutants have a stronger defective invasion phenotype than sho1 mutants when tested on certain solid media that use mannitol or sucrose as a carbon source or under hypoxia. Interestingly, Msb2 contributes to growth under conditions of high osmolarity when both branches of the HOG pathway are altered, as triple ssk1 msb2 sho1 mutants (but not any single or double mutant) are osmosensitive. However, this phenomenon is independent of the presence of Hog1, as Hog1 phosphorylation, Hog1 translocation to the nucleus, and glycerol accumulation are not affected in this mutant following an osmotic shock. These results reveal essential functions in morphogenesis, invasion, cell wall biogenesis, and growth under conditions of high osmolarity for Msb2 in C. albicans and suggest the divergence and specialization of this signaling pathway in filamentous fungi.

scholarly journals The Mitogen-Activated Protein Kinase BcSak1 of Botrytis cinerea Is Required for Pathogenic Development and Has Broad Regulatory Functions Beyond Stress Response

2012 ◽  
Vol 25 (6) ◽  
pp. 802-816 ◽  
Author(s):  
Jens Heller ◽  
Nadja Ruhnke ◽  
José Juan Espino ◽  
Michelli Massaroli ◽  
Isidro Gonzalez Collado ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Protein Kinase ◽  
Osmotic Stress ◽  
Botrytis Cinerea ◽  
Fluorescent Protein ◽  
Mitogen Activated Protein Kinase ◽  
In Planta ◽  
Mitogen Activated Protein

The mitogen-activated protein kinase (MAPK) BcSak1 of Botrytis cinerea is activated upon exposure to H2O2 and, hence, might be involved in coping with oxidative stress during infection. However, beside osmotic and oxidative stress sensitivity, Δbcsak1 mutants have a pleiotropic phenotype, as they do not produce conidia and are unable to penetrate unwounded host tissue. In this study, the role of BcSak1 was investigated in the stress response and during infection of French beans by Botrytis cinerea. Using a macroarray approach, it was shown that BcSak1 is only marginally involved in the specific oxidative stress response. In fact, the induction of several genes after oxidative stress treatment is BcSak1-dependent, but most of these genes are also induced under conditions of osmotic stress. The majority of genes regulated by BcSak1 are not involved in the stress response at all. Using a translational fusion of BcSak1 to green fluorescent protein, it was shown clearly that the localization of this MAPK depends on the type of stress being applied; it associates rapidly to the nucleus only under osmotic stress. Therefore, a model is proposed in which BcSak1 acts in the cytosol by activation of one or more transcription factors under oxidative stress and, at the same time, it reacts to osmotic stress by migrating to the nucleus. Interestingly, the MAPK is also involved in the regulation of secondary metabolism, as the major phytotoxins secreted by this fungus are reduced in the Δbcsak1 deletion mutant. Experiments done in planta underlined the essential role of BcSak1 in the early stages of infection, when it translocates to the nucleus and then changes to cytosolic distribution during hyphal growth within the tissue.

scholarly journals Yeast Mpk1 Cell Wall Integrity Mitogen-activated Protein Kinase Regulates Nucleocytoplasmic Shuttling of the Swi6 Transcriptional Regulator

2010 ◽  
Vol 21 (9) ◽  
pp. 1609-1619 ◽  
Author(s):  
Ki-Young Kim ◽  
Andrew W. Truman ◽  
Stefanie Caesar ◽  
Gabriel Schlenstedt ◽  
David E. Levin
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Transcriptional Activation ◽  
Transcriptional Response ◽  
Wall Stress ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Nucleocytoplasmic Shuttling ◽  
Nuclear Entry ◽  
Mitogen Activated Protein

The yeast SBF transcription factor is a heterodimer comprised of Swi4 and Swi6 that has a well defined role in cell cycle-specific transcription. SBF serves a second function in the transcriptional response to cell wall stress in which activated Mpk1 mitogen-activated protein kinase of the cell wall integrity signaling pathway forms a complex with Swi4, the DNA binding subunit of SBF, conferring upon Swi4 the ability to bind DNA and activate transcription of FKS2. Although Mpk1–Swi4 complex formation and transcriptional activation of FKS2 does not require Mpk1 catalytic activity, Swi6 is phosphorylated by Mpk1 and must be present in the Mpk1-Swi4 complex for transcriptional activation of FKS2. Here, we find that Mpk1 regulates Swi6 nucleocytoplasmic shuttling in a biphasic manner. First, formation of the Mpk1-Swi4 complex recruits Swi6 to the nucleus for transcriptional activation. Second, Mpk1 negatively regulates Swi6 by phosphorylation on Ser238, which inhibits nuclear entry. Ser238 neighbors a nuclear localization signal (NLS) whose function is blocked by phosphorylation at Ser238 in a manner similar to the regulation by Cdc28 of another Swi6 NLS, revealing a mechanism for the integration of multiple signals to a single endpoint. Finally, the Kap120 β-importin binds the Mpk1-regulated Swi6 NLS but not the Cdc28-regulated NLS.

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