Mitogen-activated protein kinases MpkA and MpkB independently affect micafungin sensitivity in Aspergillus nidulans
Akira Yoshimi1, Tomonori Fujioka, Osamu Mizutani
1a ABE Project, New Industry Creation Hatchery Center , Tohoku University , Aoba-ku Sendai , Japan.
Abstract:
The transcriptional regulation of the MAPK mpkA and cell wall-related genes in Aspergillus nidulans differs from that of their counterparts in Saccharomyces cerevisiae. The A. nidulans MAPK MpkB is putatively orthologous to the yeast MAPKs Kss1p and Fus3p. To investigate MpkB and its contribution to cell wall integrity in A. nidulans, we constructed mpkB-disruptant (mpkB∆) strains. We previously showed that mpkA∆ strains exhibited reduced colony growth and increased sensitivity to the β-1,3-glucan synthase inhibitor micafungin. Like mpkA∆ strains, mpkB∆ strains exhibited slight growth retardation and increased sensitivity to micafungin. Although MpkB-dependent signaling modulated the transcription of some cell wall-related genes, the sugar composition of cell wall fractions was similar among wild-type, mpkA∆, and mpkB∆ strains. To elucidate the relationship between MpkA and MpkB pathways, we compared conditional mutants of mpkB with those with mpkA deletion. Sensitivity testing suggested that MpkA and MpkB additively contribute to micafungin activity in A. nidulans.
Insights
In Aspergillus nidulans, both MpkA and MpkB mitogen-activated protein kinase pathways are crucial for cell wall integrity and sensitivity to micafungin, acting additively to regulate fungal growth.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Transcriptional regulation of MAPK pathways and cell wall genes varies between fungal species like Aspergillus nidulans and Saccharomyces cerevisiae.
- Mitogen-activated protein kinase (MAPK) MpkB in A. nidulans is a potential ortholog of yeast MAPKs Kss1p and Fus3p.
Purpose of the Study:
- To investigate the role of MpkB in maintaining cell wall integrity in A. nidulans.
- To understand the relationship between MpkA and MpkB signaling pathways in A. nidulans.
Main Methods:
- Construction and analysis of mpkB-disruptant (mpkB∆) strains in A. nidulans.
- Phenotypic analysis including colony growth and sensitivity to micafungin.
- Comparison of conditional mpkB mutants with mpkA deletion strains.
Main Results:
- mpkB∆ strains showed slight growth retardation and increased sensitivity to micafungin, similar to mpkA∆ strains.
- MpkB-dependent signaling influenced the transcription of certain cell wall-related genes.
- Cell wall sugar composition remained consistent across wild-type, mpkA∆, and mpkB∆ strains.
- MpkA and MpkB pathways were found to contribute additively to micafungin activity.
Conclusions:
- MpkB plays a role in cell wall integrity and micafungin sensitivity in A. nidulans.
- MpkA and MpkB signaling pathways exhibit an additive interaction in regulating fungal response to micafungin.
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