scholarly journals Colletotrichum higginsianum Mitogen-Activated Protein Kinase ChMK1: Role in Growth, Cell Wall Integrity, Colony Melanization, and Pathogenicity

2016 ◽  
Vol 7 ◽  
Author(s):  
Wei Wei ◽  
Ying Xiong ◽  
Wenjun Zhu ◽  
Nancong Wang ◽  
Guogen Yang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Colletotrichum Higginsianum ◽  
Mitogen Activated Protein

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 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.

scholarly journals Putative Membrane Receptors Contribute to Activation and Efficient Signaling of Mitogen-Activated Protein Kinase Cascades during Adaptation of Aspergillus fumigatus to Different Stressors and Carbon Sources

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Lilian Pereira Silva ◽  
Dean Frawley ◽  
Leandro José de Assis ◽  
Ciara Tierney ◽  
Alastair B. Fleming ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Aspergillus Fumigatus ◽  
Fungal Pathogen ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Hog Pathway ◽  
Content Type ◽  
High Osmolarity Glycerol ◽  
Mitogen Activated Protein

ABSTRACT The high-osmolarity glycerol (HOG) response pathway is a multifunctional signal transduction pathway that specifically transmits ambient osmotic signals. Saccharomyces cerevisiae Hog1p has two upstream signaling branches, the sensor histidine kinase Sln1p and the receptor Sho1p. The Sho1p branch includes two other proteins, the Msb2p mucin and Opy2p. Aspergillus fumigatus is the leading cause of pulmonary fungal diseases. Here, we investigated the roles played by A. fumigatus SlnASln1p, ShoASho1p, MsbAMsb2p, and OpyAOpy2p putative homologues during the activation of the mitogen-activated protein kinase (MAPK) HOG pathway. The shoA, msbA, and opyA singly and doubly null mutants are important for the cell wall integrity (CWI) pathway, oxidative stress, and virulence as assessed by a Galleria mellonella model. Genetic interactions of ShoA, MsbA, and OpyA are also important for proper activation of the SakAHog1p and MpkASlt2 cascade and the response to osmotic and cell wall stresses. Comparative label-free quantitative proteomics analysis of the singly null mutants with the wild-type strain upon caspofungin exposure indicates that the absence of ShoA, MsbA, and OpyA affects the osmotic stress response, carbohydrate metabolism, and protein degradation. The putative receptor mutants showed altered trehalose and glycogen accumulation, suggesting a role for ShoA, MsbA, and OpyA in sugar storage. Protein kinase A activity was also decreased in these mutants. We also observed genetic interactions between SlnA, ShoA, MsbA, and OpyA, suggesting that both branches are important for activation of the HOG/CWI pathways. Our results help in the understanding of the activation and modulation of the HOG and CWI pathways in this important fungal pathogen. IMPORTANCE Aspergillus fumigatus is an important human-pathogenic fungal species that is responsible for a high incidence of infections in immunocompromised individuals. A. fumigatus high-osmolarity glycerol (HOG) and cell wall integrity pathways are important for the adaptation to different forms of environmental adversity such as osmotic and oxidative stresses, nutrient limitations, high temperatures, and other chemical and mechanical stresses that may be produced by the host immune system and antifungal drugs. Little is known about how these pathways are activated in this fungal pathogen. Here, we characterize four A. fumigatus putative homologues that are important for the activation of the yeast HOG pathway. A. fumigatus SlnASln1p, ShoASho1p, MsbAMsb2p, and OpyAOpy2p are genetically interacting and are essential for the activation of the HOG and cell wall integrity pathways. Our results contribute to the understanding of A. fumigatus adaptation to the host environment.

scholarly journals Pkh1 and Pkh2 Differentially Phosphorylate and Activate Ypk1 and Ykr2 and Define Protein Kinase Modules Required for Maintenance of Cell Wall Integrity

2002 ◽  
Vol 13 (9) ◽  
pp. 3005-3028 ◽  
Author(s):  
Françoise M. Roelants ◽  
Pamela D. Torrance ◽  
Natalie Bezman ◽  
Jeremy Thorner
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Kinase Domain ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Restrictive Temperature ◽  
Mitogen Activated Protein ◽  
Catalytically Active ◽  
Inducible Protein ◽  
Mammalian Protein

Saccharomyces cerevisiae Pkh1 and Pkh2 are functionally redundant homologs of mammalian protein kinase, phosphoinositide-dependent protein kinase-1. They activate two closely related, functionally redundant enzymes, Ypk1 and Ykr2 (homologs of mammalian protein kinase, serum- and glucocorticoid-inducible protein kinase). We found that Ypk1 has a more prominent role than Ykr2 in mediating their shared essential function. Considerable evidence demonstrated that Pkh1 preferentially activates Ypk1, whereas Pkh2 preferentially activates Ykr2. Loss of Pkh1 (but not Pkh2) reduced Ypk1 activity; conversely, Pkh1 overexpression increased Ypk1 activity more than Pkh2 overexpression. Loss of Pkh2 reduced Ykr2 activity; correspondingly, Pkh2 overexpression increased Ykr2 activity more than Pkh1 overexpression. When overexpressed, a catalytically active C-terminal fragment (kinase domain) of Ypk1 was growth inhibitory; loss of Pkh1 (but not Pkh2) alleviated toxicity. Loss of Pkh2 (but not Pkh1) exacerbated the slow growth phenotype of aypk1Δ strain. This Pkh1-Ypk1 and Pkh2-Ykr2 dichotomy is not absolute because all double mutants (pkh1Δ ypk1Δ, pkh2Δ ypk1Δ, pkh1Δ ykr2Δ, and pkh2Δ ykr2Δ) were viable. Compartmentation contributes to selectivity because Pkh1 and Ypk1 were located exclusively in the cytosol, whereas Pkh2 and Ykr2 entered the nucleus. At restrictive temperature,ypk1-1tsykr2Δ cells lysed rapidly, but not in medium containing osmotic support. Dosage and extragenic suppressors were selected. Overexpression of Exg1 (major exoglucanase), or loss of Kex2 (endoprotease involved in Exg1 processing), rescued growth at high temperature. Viability was also maintained by PKC1 overexpression or an activated allele of the downstream protein kinase (BCK1-20). Conversely, absence of Mpk1 (distal mitogen-activated protein kinase of thePKC1 pathway) was lethal inypk1-1tsykr2Δ cells. Thus, Pkh1-Ypk1 and Pkh2-Ykr2 function in a novel pathway for cell wall integrity that acts in parallel with the Pkc1-dependent pathway.

scholarly journals Role of the Slt2 mitogen-activated protein kinase pathway in cell wall integrity and virulence in Candida glabrata

2010 ◽  
Vol 10 (3) ◽  
pp. 343-352 ◽  
Author(s):  
Taiga Miyazaki ◽  
Tatsuo Inamine ◽  
Shunsuke Yamauchi ◽  
Yosuke Nagayoshi ◽  
Tomomi Saijo ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Candida Glabrata ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

scholarly journals Role of the Cell Wall Integrity and Filamentous Growth Mitogen-Activated Protein Kinase Pathways in Cell Wall Remodeling during Filamentous Growth

2009 ◽  
Vol 8 (8) ◽  
pp. 1118-1133 ◽  
Author(s):  
Barbara Birkaya ◽  
Abhiram Maddi ◽  
Jyoti Joshi ◽  
Stephen J. Free ◽  
Paul J. Cullen
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Filamentous Growth ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Cell Wall Integrity Pathway ◽  
Cell Wall Remodeling ◽  
Mitogen Activated Protein ◽  
Cell Cell

ABSTRACT Many fungal species including pathogens exhibit filamentous growth (FG) as a means of foraging for nutrients. Genetic screens were performed to identify genes required for FG in the budding yeast Saccharomyces cerevisiae. Genes encoding proteins with established functions in transcriptional activation (MCM1, MATα2, PHD1, MSN2, SIR4, and HMS2), cell wall integrity (MPT5, WSC2, and MID2), and cell polarity (BUD5) were identified as potential regulators of FG. The transcription factors MCM1 and MATα2 induced invasive growth by promoting diploid-specific bipolar budding in haploid cells. Components of the cell wall integrity pathway including the cell surface proteins Slg1p/Wsc1p, Wsc2p, Mid2p, and the mitogen-activated protein kinase (MAPK) Slt2p/Mpk1p contributed to multiple aspects of the FG response including cell elongation, cell-cell adherence, and agar invasion. Mid2p and Wsc2p stimulated the FG MAPK pathway through the signaling mucin Msb2p and components of the MAPK cascade. The FG pathway contributed to cell wall integrity in parallel with the cell wall integrity pathway and in opposition with the high osmolarity glycerol response pathway. Mass spectrometry approaches identified components of the filamentous cell wall including the mucin-like proteins Msb2p, Flo11p, and subtelomeric (silenced) mucin Flo10p. Secretion of Msb2p, which occurs as part of the maturation of the protein, was inhibited by the ß-1,3-glucan layer of the cell wall, which highlights a new regulatory aspect to cell wall remodeling in this organism. Disruption of ß-1,3-glucan linkages induced mucin shedding and resulted in defects in cell-cell adhesion and invasion of cells into the agar matrix.

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