G-Protein β Subunit of
            <i>Cochliobolus heterostrophus</i>
            Involved in Virulence, Asexual and Sexual Reproductive Ability, and Morphogenesis

Ganem, Sherif; Lu, Shunwen; Lee, Bee-Na; Chou, David Yu-Te; Hadar, Ruthi; Turgeon, B. Gillian; Horwitz, Benjamin A.

doi:10.1128/ec.4.2.493.2005

Cited by 6 publications

(9 citation statements)

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“…1a). After in silico analysis and literature review (Ganem et al, 2004;Pöggeler & Kück, 2004;Shim et al, 2006;Smith et al, 1999), we hypothesized that the C terminus of Fsr1, containing the WD40 repeats motif, is directly associated with maize stalk rot virulence. To test our hypothesis, we first complemented the FSR1 knockout strain (Dfsr1) with mutated versions of the FSR1 gene (Fig.…”

Section: Resultsmentioning

confidence: 99%

The coiled-coil protein-binding motif in Fusarium verticillioides Fsr1 is essential for maize stalk rot virulence

Yamamura

Shim

2008

Microbiology

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Fusarium verticillioides (Sacc.) Nirenberg (teleomorph Gibberella moniliformis Wineland) is one of the key pathogens of maize stalk rot disease. However, a clear understanding of stalk rot pathogenesis is still lacking. Previously, we identified the F. verticillioides FSR1 gene, which plays a key role in fungal virulence and sexual mating. The predicted Fsr1 protein contains multiple protein-binding domains, namely a caveolin-binding domain, a coiled-coil structure, and a calmodulin-binding motif at the N terminus and a WD40 repeat domain at the C terminus. Fsr1 shares significant similarity to a family of striatin proteins that play a critical role in cellular mechanisms that regulate a variety of developmental processes. Significantly, FSR1 function is conserved in Fusarium graminearum, where it also plays a direct role in pathogenesis. In this study, our goal was to determine the motif(s) in Fsr1 that are directly associated with fungal virulence. We complemented the FSR1 knockout (Dfsr1) strain with mutated versions of the FSR1 gene, and determined that the Fsr1 C-terminal WD40 repeat domain is dispensable for vegetative growth and maize stalk rot virulence. We also examined the potential link between FSR1-mediated virulence and cell wall-degrading enzyme (a-amylase, pectinase and cellulase) activities. Further characterization of the N-terminal region revealed that the coiled-coil structure is essential for virulence in F. verticillioides. The coiled-coil domain is involved in a variety of protein-protein interactions in eukaryotic systems, and thus we hypothesize that the interaction between Fsr1 and the putative Fsr1-binding protein triggers downstream gene signalling that is associated with F. verticillioides virulence.

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Section: Resultsmentioning

confidence: 99%

The coiled-coil protein-binding motif in Fusarium verticillioides Fsr1 is essential for maize stalk rot virulence

Yamamura

Shim

2008

Microbiology

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“…Encoded proteins in groups I and III are related to the mammalian G␣ i and G␣ s families, respectively, but group II fungal G␣ proteins have no mammalian counterpart (1,4,14,22,33,53). Interestingly, the corn smut fungus Ustilago maydis contains a unique fourth G␣-encoding gene, and Saccharomyces cerevisiae contains only two G␣ proteins (10,57).…”

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confidence: 99%

“…Irrespective of the observed numerical variation, G␣ proteins regulate a variety of cellular and developmental responses (4). For plant-pathogenic fungi, G␤-encoding genes have been characterized functionally (9,14,22,27,31,48,52). Apart from the fact that individual G␣-encoding genes and the G␤-encoding gene have been demonstrated to regulate growth, reproduction, and virulence, comparative functional characterization of all G␣-encoding genes has been reported only for a few plantpathogenic fungi, including Magnaporthe grisea, Cryphonectria parasitica, and U. maydis (5,41,57).…”

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confidence: 99%

Gα and Gβ Proteins Regulate the Cyclic AMP Pathway That Is Required for Development and Pathogenicity of the Phytopathogen Mycosphaerella graminicola

et al. 2009

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We identified and functionally characterized genes encoding three G␣ proteins and one G␤ protein in the dimorphic fungal wheat pathogen Mycosphaerella graminicola, which we designated MgGpa1, MgGpa2, MgGpa3, and MgGpb1, respectively. Sequence comparisons and phylogenetic analyses showed that MgGPA1 and MgGPA3 are most related to the mammalian G␣ i and G␣ s families, respectively, whereas MgGPA2 is not related to either of these families. On potato dextrose agar (PDA) and in yeast glucose broth (YGB), MgGpa1 mutants produced significantly longer spores than those of the wild type (WT), and these developed into unique fluffy mycelia in the latter medium, indicating that this gene negatively controls filamentation. MgGpa3 mutants showed more pronounced yeast-like growth accompanied with hampered filamentation and secreted a dark-brown pigment into YGB. Germ tubes emerging from spores of MgGpb1 mutants were wavy on water agar and showed a nested type of growth on PDA that was due to hampered filamentation, numerous cell fusions, and increased anastomosis. Intracellular cyclic AMP (cAMP) levels of MgGpb1 and MgGpa3 mutants were decreased, indicating that both genes positively regulate the cAMP pathway, which was confirmed because the WT phenotype was restored by adding cAMP to these mutant cultures. The cAMP levels in MgGpa1 mutants and the WT were not significantly different, suggesting that this gene might be dispensable for cAMP regulation. In planta assays showed that mutants of MgGpa1, MgGpa3, and MgGpb1 are strongly reduced in pathogenicity. We concluded that the heterotrimeric G proteins encoded by MgGpa3 and MgGpb1 regulate the cAMP pathway that is required for development and pathogenicity in M. graminicola.

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“…At the output of these cascades there are sets of target genes, whose expression began to be studied in recent years. We previously identified roles for the individual G-protein Gα and Gβ subunits Degani et al 2004;Ganem et al 2004;Degani 2013a,b) and for the MAPK (Lev et al 1999) in C. heterostrophus development, reproduction, and pathogenicity (summarised in Degani 2013a). To date, little knowledge exists on downstream signalling elements of these cascades in this species.…”

Section: Discussionmentioning

confidence: 99%

“…In Cochliobolus heterostrophus, the agent of Southern corn leaf blight, G-protein subunits, Ga (CGA1) and Gb (CGB1), as well as a mitogen-activated protein kinase (MAPK, CHK1), participate in several developmental pathways. Disruption studies of these signalling components result in severe phenotypes, including loss of the normal meandering hyphal growth pattern on hard surfaces, lack of appressorium formation and defects in mating and virulence Lev et al 1999;Degani et al 2004;Ganem et al 2004;Degani 2013a,b). An epistatic relationship may exist between the two branches of the G-protein pathways (Degani 2013a).…”

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confidence: 99%

Cochliobolus heterostrophus T-toxin gene expression modulation via G protein and MAPK pathways

Degani

2015

Plant Prot. Sci.

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Degani O. (2015): Cochliobolus heterostrophus T-toxin gene expression modulation via G protein and MAPK pathways. Plant Protect Sci., 51: 53-60.The role of G-protein and mitogen-activated protein kinase (MAPK) in filamentous fungi has been studied for over a decade, but downstream elements are less known. Here, we used microarray and Northern blot analysis to examine the involvement of these signalling pathways in controlling the known Cochliobolus heterostrophus T-toxin biosynthetic gene, DEC1, whose control is important in epidemic prevention. Comparison of the expression profile in wild-type strains and in G-protein and MAPK signalling deficient mutants revealed a unique, environmental-dependent control mechanism for the DEC1 gene. The results suggest, for the first time, a possible role in pathogenicity for the G-protein α2 subunit in this organism, and hint to a common role of G-protein α1 and β1 subunits and MAPK in maintaining accurate levels of this toxin during pathogenesis.

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G-Protein β Subunit of Cochliobolus heterostrophus Involved in Virulence, Asexual and Sexual Reproductive Ability, and Morphogenesis

Cited by 6 publications

References 0 publications

The coiled-coil protein-binding motif in Fusarium verticillioides Fsr1 is essential for maize stalk rot virulence

The coiled-coil protein-binding motif in Fusarium verticillioides Fsr1 is essential for maize stalk rot virulence

Gα and Gβ Proteins Regulate the Cyclic AMP Pathway That Is Required for Development and Pathogenicity of the Phytopathogen Mycosphaerella graminicola

Cochliobolus heterostrophus T-toxin gene expression modulation via G protein and MAPK pathways

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