scholarly journals Evolutionary Reshaping of Fungal Mating Pathway Scaffold Proteins

mBio ◽  
2011 ◽  
Vol 2 (1) ◽  
Author(s):  
Pierre Côte ◽  
Traian Sulea ◽  
Daniel Dignard ◽  
Cunle Wu ◽  
Malcolm Whiteway
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Map Kinase ◽  
Scaffold Proteins ◽  
Cellular Polarity ◽  
Pathogenic Yeast ◽  
Content Type ◽  
Fungal Lineage ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Mating Pathway

ABSTRACTScaffold proteins play central roles in the function of many signaling pathways. Among the best-studied examples are the Ste5 and Far1 proteins of the yeastSaccharomyces cerevisiae. These proteins contain three conserved modules, the RING and PH domains, characteristic of some ubiquitin-ligating enzymes, and a vWA domain implicated in protein-protein interactions. In yeast, Ste5p regulates the mating pathway kinases while Far1p coordinates the cellular polarity machinery. Within the fungal lineage, theBasidiomycetesand thePezizomycetescontain a single Far1-like protein, while severalSaccharomycotinaspecies, belonging to the CTG (Candida) clade, contain both a classic Far1-like protein and a Ste5-like protein that lacks the vWA domain. We analyzed the function ofC. albicansSte5p (Cst5p), a member of this class of structurally distinct Ste5 proteins.CST5is essential for mating and still coordinates the mitogen-activated protein (MAP) kinase (MAPK) cascade elements in the absence of the vWA domain; Cst5p interacts with the MEK kinase (MEKK)C. albicansSte11p (CaSte11p) and the MAPK Cek1 as well as with the MEK Hst7 in a vWA domain-independent manner. Cst5p can homodimerize, similar to Ste5p, but can also heterodimerize with Far1p, potentially forming heteromeric signaling scaffolds. We found direct binding between the MEKK CaSte11p and the MEK Hst7p that depends on a mobile acidic loop absent fromS. cerevisiaeSte11p but related to the Ste7-binding region within the vWA domain of Ste5p. Thus, the fungal lineage has restructured specific scaffolding modules to coordinate the proteins required to direct the gene expression, polarity, and cell cycle regulation essential for mating.IMPORTANCEThe mitogen-activated protein (MAP) kinase cascade is an extensively used signaling module in eukaryotic cells, and the ability to regulate these modules is critical for ensuring proper responses to a wide variety of stimuli. One way that cells regulate this signaling module is through scaffold proteins that insulate related pathways against cross talk, improve signaling efficiency, and ensure that signals are connected to the correct response. The Ste5 scaffold of theS. cerevisiaemating response is a well-studied representative of this class of proteins. Using bioinformatics, structural modeling, and molecular genetic approaches, we have investigated the equivalent scaffold in the pathogenic yeastCandida albicans. We show that theC. albicansprotein is structurally distinct from that ofSaccharomyces cerevisiaebut still provides similar functions. Increases in pathway complexity have been associated with changes in scaffold connectivity, and overall, the tethering capacity of the scaffolds has been more conserved than their structural organization.

scholarly journals Utilization of the Mating Scaffold Protein in the Evolution of a New Signal Transduction Pathway for Biofilm Development

mBio ◽  
2011 ◽  
Vol 2 (1) ◽  
Author(s):  
Song Yi ◽  
Nidhi Sahni ◽  
Karla J. Daniels ◽  
Kevin L. Lu ◽  
Guanghua Huang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Scaffold Protein ◽  
White Cell ◽  
Pheromone Response ◽  
Content Type ◽  
Pheromone Response Pathway ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Kinase Cascade

ABSTRACTAmong the hemiascomycetes, onlyCandida albicansmust switch from the white phenotype to the opaque phenotype to mate. In the recent evolution of this transition, mating-incompetent white cells acquired a unique response to mating pheromone, resulting in the formation of a white cell biofilm that facilitates mating. All of the upstream components of the white cell response pathway so far analyzed have been shown to be derived from the ancestral pathway involved in mating, except for the mitogen-activated protein (MAP) kinase scaffold protein, which had not been identified. Here, through binding and mutational studies, it is demonstrated that in both the opaque and the white cell pheromone responses, Cst5 is the scaffold protein, supporting the evolutionary scenario proposed. Although Cst5 plays the same role in tethering the MAP kinases as Ste5 does inSaccharomyces cerevisiae, Cst5 is approximately one-third the size and has only one rather than four phosphorylation sites involved in activation and cytoplasmic relocalization.IMPORTANCECandida albicansmust switch from white to opaque to mate. Opaque cells then release pheromone, which not only induces cells to mate but also in a unique fashion induces mating-incompetent white cells to form biofilms that facilitate opaque cell mating. All of the tested upstream components of the newly evolved white cell pheromone response pathway, from the receptor to the mitogen-activated protein (MAP) kinase cascade, are the same as those of the conserved opaque cell response pathway. One key element, however, remained unidentified, the scaffold protein for the kinase cascade. Here, we demonstrate that Cst5, a homolog of theSaccharomyces cerevisiaescaffold protein Ste5, functions as the scaffold protein in both the opaque and the white cell pheromone responses. Pheromone induces Cst5 phosphorylation, which is involved in activation and cytoplasmic localization of Cst5. However, Cst5 contains only one phosphorylation site, not four as in theS. cerevisiaeortholog Ste5. These results support the hypothesis that the entire upper portion of the newly evolved white cell pheromone response pathway is derived from the conserved pheromone response pathway in the mating process.

scholarly journals Methylglyoxal Activates the Target of Rapamycin Complex 2-Protein Kinase C Signaling Pathway in Saccharomyces cerevisiae

2015 ◽  
Vol 35 (7) ◽  
pp. 1269-1280 ◽  
Author(s):  
Wataru Nomura ◽  
Yoshiharu Inoue
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Map Kinase ◽  
Target Of Rapamycin ◽  
Dependent Manner ◽  
Content Type ◽  
Protein Levels ◽  
Map Kinase Cascade ◽  
Phosphorylated Akt ◽  
Mitogen Activated Protein ◽  
Kinase Cascade

Methylglyoxal is a typical 2-oxoaldehyde derived from glycolysis. We show here that methylglyoxal activates the Pkc1-Mpk1 mitogen-activated protein (MAP) kinase cascade in a target of rapamycin complex 2 (TORC2)-dependent manner in the budding yeastSaccharomyces cerevisiae. We demonstrate that TORC2 phosphorylates Pkc1 at Thr1125and Ser1143. Methylglyoxal enhanced the phosphorylation of Pkc1 at Ser1143, which transmitted the signal to the downstream Mpk1 MAP kinase cascade. We found that the phosphorylation status of Pkc1T1125affected the phosphorylation of Pkc1 at Ser1143, in addition to its protein levels. Methylglyoxal activated mammalian TORC2 signaling, which, in turn, phosphorylated Akt at Ser473. Our results suggest that methylglyoxal is a conserved initiator of TORC2 signaling among eukaryotes.

scholarly journals Coordination of the mating and cell integrity mitogen-activated protein kinase pathways in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (11) ◽  
pp. 6517-6525 ◽  
Author(s):  
B M Buehrer ◽  
B Errede
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Cell Integrity ◽  
Mating Partner ◽  
Kinase Activation ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Mating Pathway ◽  
Transcriptional Output

Mating pheromone stimulates a mitogen-activated protein (MAP) kinase activation pathway in Saccharomyces cerevisiae that induces cells to differentiate and form projections oriented toward the gradient of pheromone secreted by a mating partner. The polarized growth of mating projections involves new cell wall synthesis, a process that relies on activation of the cell integrity MAP kinase, Mpk1. In this report, we show that Mpk1 activation during pheromone induction requires the transcriptional output of the mating pathway and protein synthesis. Consequently, Mpk1 activation occurs subsequent to the activation of the mating pathway MAP kinase cascade. Additionally, Spa2 and Bni1, a formin family member, are two coil-coil-related proteins that are involved in the timing and other aspects of mating projection formation. Both proteins also affect the timing and extent of Mpk1 activation. This correlation suggests that projection formation comprises part of the pheromone-induced signal that coordinates Mpk1 activation with mating differentiation. Stimulation of Mpk1 activity occurs through the cell integrity phosphorylation cascade and depends on Pkc1 and the redundant MAP/Erk kinases (MEKs), Mkk1 and Mkk2. Surprisingly, Mpk1 activation by pheromone was only partially impaired in cells lacking the MEK kinase Bck1. This Bck1-independent mechanism reveals the existence of an alternative activator of Mkk1/Mkk2 in some strain backgrounds that at least functions under pheromone-induced conditions.

scholarly journals The osmoregulatory pathway represses mating pathway activity in Saccharomyces cerevisiae: isolation of a FUS3 mutant that is insensitive to the repression mechanism.

1996 ◽  
Vol 16 (12) ◽  
pp. 6715-6723 ◽  
Author(s):  
J P Hall ◽  
V Cherkasova ◽  
E Elion ◽  
M C Gustin ◽  
E Winter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Map Kinase ◽  
Map Kinases ◽  
Hog Pathway ◽  
Pathway Activity ◽  
Mitogen Activated Protein ◽  
Increased Sensitivity ◽  
Mating Pathway ◽  
Single Cell Type

Mitogen-activated protein (MAP) kinase cascades are conserved signal transduction pathways that are required for eukaryotic cells to respond to a variety of stimuli. Multiple MAP kinase pathways can function within a single cell type; therefore, mechanisms that insulate one MAP kinase pathway from adventitious activations by parallel pathways may exist. We have studied interactions between the mating pheromone response and the osmoregulatory (high-osmolarity glycerol response [HOG]) pathways in Saccharomyces cerevisiae which utilize the MAP kinases Fus3p and Hog1p, respectively. Inactivating mutations in HOG pathway kinases cause an increase in the phosphotyrosine content of Fus3p, greater expression of pheromone-responsive genes, and increased sensitivity to growth arrest by pheromone. Therefore, the HOG pathway represses mating pathway activity. In a HOG1+ strain, Fus3p phosphotyrosine increases modestly and transiently following an increase in the extracellular osmolarity; however, it increases to a greater extent and for a sustained duration in a hog1-delta strain. Thus, the HOG-mediated repression of mating pathway activity may insulate the mating pathway from activation by osmotic stress. A FUS3 allele whose gene product is resistant to the HOG-mediated repression of its phosphotyrosine content has been isolated. This mutant encodes an amino acid substitution in the highly conserved DPXDEP motif in subdomain XI. Other investigators have shown that the corresponding amino acid is also mutated in a gain-of-function allele of the MAP kinase encoded by the rolled locus in Drosophila melanogaster. These data suggest that the DPXDEP motif plays a role in the negative regulation of MAP kinases.

scholarly journals Mitogen-Activated Protein (MAP) Kinase Pathways: Regulation and Physiological Functions*

2001 ◽  
Vol 22 (2) ◽  
pp. 153-183 ◽  
Author(s):  
Gray Pearson ◽  
Fred Robinson ◽  
Tara Beers Gibson ◽  
Bing-e Xu ◽  
Mahesh Karandikar ◽  
...  
Keyword(s):  
Map Kinase ◽  
Physiological Functions ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathways

MKK1 and MKK2, which encode Saccharomyces cerevisiae mitogen-activated protein kinase-kinase homologs, function in the pathway mediated by protein kinase C

1993 ◽  
Vol 13 (5) ◽  
pp. 3076-3083
Author(s):  
K Irie ◽  
M Takase ◽  
K S Lee ◽  
D E Levin ◽  
H Araki ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Map Kinase ◽  
Protein Kinases ◽  
Cell Lysis ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Kinase C ◽  
Mitogen Activated Protein

The PKC1 gene of Saccharomyces cerevisiae encodes a homolog of mammalian protein kinase C that is required for normal growth and division of yeast cells. We report here the isolation of the yeast MKK1 and MKK2 (for mitogen-activated protein [MAP] kinase-kinase) genes which, when overexpressed, suppress the cell lysis defect of a temperature-sensitive pkc1 mutant. The MKK genes encode protein kinases most similar to the STE7 product of S. cerevisiae, the byr1 product of Schizosaccharomyces pombe, and vertebrate MAP kinase-kinases. Deletion of either MKK gene alone did not cause any apparent phenotypic defects, but deletion of both MKK1 and MKK2 resulted in a temperature-sensitive cell lysis defect that was suppressed by osmotic stabilizers. This phenotypic defect is similar to that associated with deletion of the BCK1 gene, which is thought to function in the pathway mediated by PCK1. The BCK1 gene also encodes a predicted protein kinase. Overexpression of MKK1 suppressed the growth defect caused by deletion of BCK1, whereas an activated allele of BCK1 (BCK1-20) did not suppress the defect of the mkk1 mkk2 double disruption. Furthermore, overexpression of MPK1, which encodes a protein kinase closely related to vertebrate MAP kinases, suppressed the defect of the mkk1 mkk2 double mutant. These results suggest that MKK1 and MKK2 function in a signal transduction pathway involving the protein kinases encoded by PKC1, BCK1, and MPK1. Genetic epistasis experiments indicated that the site of action for MKK1 and MKK2 is between BCK1 and MPK1.

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