Effect of cell wall integrity stress and RlmA transcription factor on asexual development and autolysis in Aspergillus nidulans

Kovács, Zsuzsanna; Szarka, Máté; Kovács, Szilvia; Boczonádi, Imre; Emri, Tamás; Abe, Keietsu; Pusztahelyi, Tünde

doi:10.1016/j.fgb.2013.02.004

Cited by 53 publications

(44 citation statements)

References 60 publications

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“…8B). In A. nidulans, extracellular chitinase and protease genes were highly transcribed in CreA null mutants (44). Consistent with this, many protease and chitinase genes were evidently upregulated (P Ͻ 0.05) in the ⌬MrSkn7 mutant compared to the WT (Fig.…”

Section: Mrskn7 Functions As a Transcription Factorsupporting

confidence: 72%

“…For example, a homolog (MAA_04270, 62% identity) of yeast oligosaccharyltransferase gene, Stt3, involved in the biosynthesis of cell wall ␤-1,6-glucan (22, 42) was downregulated Ͼ2-fold in the mutant cells. In addition, a homolog (MAA_08135, 55% identity) of the Aspergillus nidulans transcription factor RlmA, which contributes to cell wall chitin accumulation (43,44), was downregulated Ͼ3-fold in the ⌬MrSkn7 mutant compared to the WT (Fig. 8B).…”

Section: Mrskn7 Functions As a Transcription Factormentioning

confidence: 99%

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MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

Shang

Chen

et al. 2015

Eukaryot Cell

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Two-component signaling pathways generally include sensor histidine kinases and response regulators. We identified an ortholog of the response regulator protein Skn7 in the insect-pathogenic fungus Metarhizium robertsii, which we named MrSkn7. Gene deletion assays and functional characterizations indicated that MrSkn7 functions as a transcription factor. The MrSkn7 null mutant of M. robertsii lost the ability to sporulate and had defects in cell wall biosynthesis but was not sensitive to oxidative and osmotic stresses compared to the wild type. However, the mutant was able to produce spores under salt stress. Insect bioassays using these spores showed that the virulence of the mutant was significantly impaired compared to that of the wild type due to the failures to form the infection structure appressorium and evade host immunity. In particular, deletion of MrSkn7 triggered cell autolysis with typical features such as cell vacuolization, downregulation of repressor genes, and upregulation of autolysis-related genes such as extracellular chitinases and proteases. Promoter binding assays confirmed that MrSkn7 could directly or indirectly control different putative target genes. Taken together, the results of this study help us understand the functional divergence of Skn7 orthologs as well as the mechanisms underlying the development and control of virulence in insect-pathogenic fungi. Both prokaryotes and eukaryotes have developed complicated systems to sense and adapt to changing environments. In bacteria, sensing and processing of environmental stimuli largely rely on two-component signal (TCS) transduction pathways that consist of a membrane-bound histidine kinase receptor and a corresponding response regulator (RR) (1, 2). Similar TCS systems are also present in fungi, and the mechanisms underlying their function have been well studied in the budding yeast Saccharomyces cerevisiae (3, 4). The TCS pathway consists of a sensor kinase, Sln1, and two response regulators, Ssk1 and Skn7 (5, 6). The cytosolic Ssk1 controls the Hog1 mitogen-activated protein kinase pathway, while the highly conserved Skn7 functions as a stress response transcription factor that consists of an N-terminal HSF (heat shock factor)-type DNA binding domain and a C-terminal RR receiver domain (5). The orthologs of Skn7 in yeasts and different filamentous fungi generally contribute to cell wall integrity, sporulation, osmotic stress, and oxidative stress (5). Interestingly, deletion of MoSkn7 (Magnaporthe oryzae Skn7) in M. oryzae (7), FgSkn7 (Fusarium graminearum Skn7) in F. graminearum (8), and BcSkn7 (Botrytis cinerea Skn7) in B. cinerea (9) did not impair fungal virulence and thereby the ability to infect their respective plant hosts. In contrast, AaSkn7 (Alternaria alternata Skn7) is required by A. alternata to infect citrus (10). In mammalian pathogens, the virulence of Candida albicans and Cryptococcus neoformans were attenuated by the deletion of CaSkn7 (C. albicans Skn7) (11) and CnSkn7 (C. neoformans Skn7) (12), respectively, compa...

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Section: Mrskn7 Functions As a Transcription Factorsupporting

confidence: 72%

Section: Mrskn7 Functions As a Transcription Factormentioning

confidence: 99%

MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

Shang

Chen

et al. 2015

Eukaryot Cell

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“…Recently, RlmA has been shown to be involved in the regulation of brlA expression (Kovács et al 2013 ). Because BrlA is a transcription factor that has a crucial role in asexual development (see following), the CWI signaling pathway and asexual development signaling pathway are suggested to be somewhat related.…”

Section: Function Of Pkc In the Cell Wall Integrity Signaling Pathwaymentioning

confidence: 99%

Protein Kinase C of Filamentous Fungi and Its Roles in the Stresses Affecting Hyphal Morphogenesis and Conidiation

Horiuchi

Katayama

2015

Stress Biology of Yeasts and Fungi

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Protein kinase C (PKC) is known to play pivotal roles in the various signal transduction pathways in mammalian cells. Its functions have been extensively explored in mammalian cells, whereas those of the PKC of fi lamentous fungi remain largely unknown, with the exception that PKC is known to function in the cell wall integrity signaling pathway similar to that in the yeast Saccharomyces cerevisiae . Recent advances in the functional analyses of Aspergillus nidulans PKC suggest that it has functions in germination, hyphal morphogenesis, and spore formation under heat stress. These functions are suppression of apoptosis induction and the establishment of cell polarity during germination, reestablishment of hyphal polarity after depolarization, and repression of conidiation. In this chapter, we present these functions of PKC and describe them in detail.

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“…In various other fungi, Rlm1 has been shown to be involved in the regulation of expression of some cell wall-related biosynthetic enzymes (Damveld et al 2005;Kovacs et al 2013;Levin 2011;Delgado-Silva et al 2014), yet the involvement of Rlm1p homologs in the CWI pathway in filamentous fungi is by far less clear than that established in S. cerevisiae.…”

Section: Introductionmentioning

confidence: 99%

Regulation of Neurospora crassa cell wall remodeling via the cot-1 pathway is mediated by gul-1

Herold

Yarden

2016

Curr Genet

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Impairment of the Neurospora crassa Nuclear DBF2-related kinase-encoding gene cot-1 results in pleiotropic effects, including abnormally thick hyphal cell walls and septa. An increase in the transcript abundance of genes encoding chitin and glucan synthases and the chitinase gh18-5, but not the cell wall integrity pathway transcription factor rlm-1, accompany the phenotypic changes observed. Deletion of chs-5 or chs-7 in a cot-1 background results in a reduction of hyperbranching frequency characteristic of the cot-1 parent. gul-1 (a homologue of the yeast SSD1 gene) encodes a translational regulator and has been shown to partially suppress cot-1. We demonstrate that the high expression levels of the cell wall remodeling genes analyzed is curbed, and reaches near wild type levels, when gul-1 is inactivated. This is accompanied by morphological changes that include reduced cell wall thickness and restoration of normal chitin levels. We conclude that gul-1 is a mediator of cell wall remodeling within the cot-1 pathway.

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Effect of cell wall integrity stress and RlmA transcription factor on asexual development and autolysis in Aspergillus nidulans

Cited by 53 publications

References 60 publications

MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

MrSkn7 Controls Sporulation, Cell Wall Integrity, Autolysis, and Virulence in Metarhizium robertsii

Protein Kinase C of Filamentous Fungi and Its Roles in the Stresses Affecting Hyphal Morphogenesis and Conidiation

Regulation of Neurospora crassa cell wall remodeling via the cot-1 pathway is mediated by gul-1

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