The <i>Cryptococcus neoformans STE11α</i> gene is similar to other fungal mitogen‐activated protein kinase kinase kinase (MAPKKK) genes but is mating type specific

Clarke, David; Woodlee, G. L.; McClelland, Carol M.; Seymour, T. S.; Wickes, Brian L.

doi:10.1046/j.1365-2958.2001.02375.x

Cited by 61 publications

(53 citation statements)

References 58 publications

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“…In the absence of kpp4, fuz7, or kpp2, pheromone-induced b gene expression was prevented. However, with respect to pheromone-responsive a gene expression the picture is different: mfa1 induction is not affected in kpp4 and fuz7 deletion strains (41) (2,16,33), the pheromone MAPK cascade is not essential for cell fusion in U. maydis. This indicates that at least one additional pathway must participate.…”

Section: Discussionmentioning

confidence: 98%

Mating and Pathogenic Development of the Smut Fungus Ustilago maydis Are Regulated by One Mitogen-Activated Protein Kinase Cascade

et al. 2003

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In the phytopathogenic fungus Ustilago maydis, pheromone-mediated cell fusion is a prerequisite for the generation of the infectious dikaryon. The pheromone signal elevates transcription of the pheromone genes and elicits formation of conjugation hyphae. Cyclic AMP and mitogen-activated protein kinase (MAPK) signaling are involved in this process. The MAPK cascade is presumed to be composed of Ubc4 (MAPK kinase kinase), Fuz7 (MAPK kinase), and Ubc3/Kpp2 (MAPK). We isolated the kpp4 gene and found it to be allelic to ubc4. Epistasis analyses with constitutively active alleles of kpp4 and fuz7 substantiate that Kpp4, Fuz7, and Kpp2/Ubc3 are components of the same module. Moreover, we demonstrate that Fuz7 activates Kpp2 and shows interactions in vitro. Signaling via this cascade regulates expression of pheromone-responsive genes, presumably through acting on the transcription factor Prf1. Interestingly, the same cascade is needed for conjugation tube formation, and this process does not involve Prf1. In addition, fuz7 as well as kpp4 deletion strains are nonpathogenic, while kpp2 deletion mutants are only attenuated in pathogenesis. Here we show that strains expressing the unphosphorylatable allele kpp2 T182A/Y184F are severely affected in tumor induction and display defects in early infection-related differentiation.

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Section: Discussionmentioning

confidence: 98%

Mating and Pathogenic Development of the Smut Fungus Ustilago maydis Are Regulated by One Mitogen-Activated Protein Kinase Cascade

et al. 2003

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“…(Kohler and Fink, 1996;Csank et al, 1998;Chen et al, 2002). By contrast, homologs of Fus3/Kss1, Ste7, and Ste11 in the basidiomycete Cryptococcus neoformans are required only for mating and cell type-specific differentiation but do not play important roles in virulence (Clarke et al, 2001). In N. crassa, the nrc-1 ascospores have a flattened appearance and are not viable (Kothe and Free, 1998).…”

Section: Discussionmentioning

confidence: 99%

A Mitogen-Activated Protein Kinase Cascade Regulating Infection-Related Morphogenesis in Magnaporthe grisea

et al. 2005

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Many fungal pathogens invade plants by means of specialized infection structures called appressoria. In the rice (Oryza sativa) blast fungus Magnaporthe grisea, the pathogenicity mitogen-activated protein (MAP) kinase1 (PMK1) kinase is essential for appressorium formation and invasive growth. In this study, we functionally characterized the MST7 and MST11 genes of M. grisea that are homologous with the yeast MAP kinase kinase STE7 and MAP kinase kinase kinase STE11. Similar to the pmk1 mutant, the mst7 and mst11 deletion mutants were nonpathogenic and failed to form appressoria. When a dominant MST7 allele with S212D and T216E mutations was introduced into the mst7 or mst11 mutant, appressorium formation was restored in the resulting transformants. PMK1 phosphorylation also was detected in the vegetative hyphae and appressoria of transformants expressing the MST7 S212D T216E allele. However, appressoria formed by these transformants failed to penetrate and infect rice leaves, indicating that constitutively active MST7 only partially rescued the defects of the mst7 and mst11 mutants. The intracellular cAMP level was reduced in transformants expressing the MST7 S212D T216E allele. We also generated MST11 mutant alleles with the sterile alpha motif (SAM) and Ras-association (RA) domains deleted. Phenotype characterizations of the resulting transformants indicate that the SAM domain but not the RA domain is essential for the function of MST11. These data indicate that MST11, MST7, and PMK1 function as a MAP kinase cascade regulating infection-related morphogenesis in M. grisea. Although no direct interaction was detected between PMK1 and MST7 or MST11 in yeast two-hybrid assays, a homolog of yeast STE50 in M. grisea directly interacted with both MST7 and MST11 and may function as the adaptor protein for the MST11-MST7-PMK1 cascade.

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“…Both the Ras (Ras1 and Ras2) and calcineurin pathways regulate the ability of this pathogenic organism to grow at 37°C (1,61,90). A mitogen-activated protein kinase cascade regulates filamentous growth and morphological differentiation in the mating process in response to activation by pheromones (14,20,32,74,90).…”

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confidence: 99%

Cryptococcus neoformansGene Expression during Murine Macrophage Infection

Fan¹,

Kraus²,

Boily³

et al. 2005

Eukaryot Cell

177

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The fungal pathogen Cryptococcus neoformans survives phagocytosis by macrophages and proliferates within, ultimately establishing latent infection as a facultative intracellular pathogen that can escape macrophage control to cause disseminated disease. This process is hypothesized to be important for C. neoformans pathogenesis; however, it is poorly understood how C. neoformans adapts to and overcomes the hostile intracellular environment of the macrophage. Using DNA microarray technology, we have investigated the transcriptional response of C. neoformans to phagocytosis by murine macrophages. The expression profiles of several genes were verified using quantitative reverse transcription-PCR and a green fluorescent protein reporter strain. Multiple membrane transporters for hexoses, amino acids, and iron were up-regulated, as well as genes involved in responses to oxidative stress. Genes involved in autophagy, peroxisome function, and lipid metabolism were also induced. Interestingly, almost the entire mating type locus displayed increased expression 24 h after internalization, suggesting an intrinsic connection between infection and the MAT locus. Genes in the Gpa1-cyclic AMP-protein kinase A pathway were also up-regulated. Both gpa1 and pka1 mutants were found to be compromised in macrophage infection, confirming the important role of this virulence pathway. A large proportion of the repressed genes are involved in ribosome-related functions, rRNA processing, and translation initiation/elongation, implicating a reduction in translation as a central response to phagocytosis. In summary, this gene expression profile allows us to interpret the adaptation of C. neoformans to the intracellular infection process and informs the search for genes encoding novel virulence attributes.

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The Cryptococcus neoformans STE11α gene is similar to other fungal mitogen‐activated protein kinase kinase kinase (MAPKKK) genes but is mating type specific

Cited by 61 publications

References 58 publications

Mating and Pathogenic Development of the Smut Fungus Ustilago maydis Are Regulated by One Mitogen-Activated Protein Kinase Cascade

Mating and Pathogenic Development of the Smut Fungus Ustilago maydis Are Regulated by One Mitogen-Activated Protein Kinase Cascade

A Mitogen-Activated Protein Kinase Cascade Regulating Infection-Related Morphogenesis in Magnaporthe grisea

Cryptococcus neoformansGene Expression during Murine Macrophage Infection

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