The Class V Chitin Synthase GenecsmAIs Crucial for the Growth of thechsA chsCDouble Mutant inAspergillus nidulans

Yamada, Eichi; Ichinomiya, Masayuki; Ohta, Akio; Horiuchi, Hiroyuki

doi:10.1271/bbb.69.87

Cited by 26 publications

(13 citation statements)

References 28 publications

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“…However, this activity is not essential for hyphal morphology, suggesting that other CHSs compensate for the loss of Mcs1 in hyphae. This notion is supported by a recent report on a triple CHS-deletion mutant in A. nidulans that suggests that the myosin-CHS csmA has a functional overlap with a class I and a class II CHS (Yamada et al, 2005). In summary, our results demonstrate that myosin-CHS is not essential for hyphal morphology in U. maydis, in contrast with reports on other fungi.…”

Section: The Class V Chs Mcs1 Is Essential For Penetration Of the Hossupporting

confidence: 88%

Polar Localizing Class V Myosin Chitin Synthases Are Essential during Early Plant Infection in the Plant Pathogenic FungusUstilago maydis

Weber¹,

Daniela²,

Thines³

et al. 2005

The Plant Cell

132

154

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Fungal chitin synthases (CHSs) form fibers of the cell wall and are crucial for substrate invasion and pathogenicity. Filamentous fungi contain up to 10 CHSs, which might reflect redundant functions or the complex biology of these fungi. Here, we investigate the complete repertoire of eight CHSs in the dimorphic plant pathogen Ustilago maydis. We demonstrate that all CHSs are expressed in yeast cells and hyphae. Green fluorescent protein (GFP) fusions to all CHSs localize to septa, whereas Chs5-GFP, Chs6-GFP, Chs7-yellow fluorescent protein (YFP), and Myosin chitin synthase1 (Mcs1)-YFP were found at growth regions of yeast-like cells and hyphae, indicating that they participate in tip growth. However, only the class IV CHS genes chs7 and chs5 are crucial for shaping yeast cells and hyphae ex planta. Although most CHS mutants were attenuated in plant pathogenicity, Dchs6, Dchs7, and Dmcs1 mutants were drastically reduced in virulence. Dmcs1 showed no morphological defects in hyphae, but Mcs1 became essential during invasion of the plant epidermis. Dmcs1 hyphae entered the plant but immediately lost growth polarity and formed large aggregates of spherical cells. Our data show that the polar class IV CHSs are essential for morphogenesis ex planta, whereas the class V myosin-CHS is essential during plant infection.

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Section: The Class V Chs Mcs1 Is Essential For Penetration Of the Hossupporting

confidence: 88%

Polar Localizing Class V Myosin Chitin Synthases Are Essential during Early Plant Infection in the Plant Pathogenic FungusUstilago maydis

Weber¹,

Daniela²,

Thines³

et al. 2005

The Plant Cell

132

154

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“…Like CFW, CR interferes with growth and causes morphological aberrations in filamentous fungi (Pancaldi et al 1984, Matsuoka et al 1985, and a wide range of cell wall mutants show hypersensitivity to the compound (e.g. Horiuchi et al 1999, Mü ller et al 2002, Oka et al 2004, Yamada et al 2005. Several cal mutant strains also show sensitivity to CR, though six of the10 are resistant to CR at one or both temperatures.…”

Section: Resultsmentioning

confidence: 99%

Isolation of cell wall mutants in Aspergillus nidulans by screening for hypersensitivity to Calcofluor White

Hill

Loprete

Momany³

et al. 2006

Mycologia

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As a first step toward identifying novel genes of wall metabolism in filamentous fungi, we have screened a collection of Aspergillus nidulans mutants for strains exhibiting hypersensitivity toward the chitin binding agent Calcofluor White (CFW). This strategy has been used previously to identify cell wall mutants in Saccharomyces cerevisiae. We have identified 10 mutants representing eight loci, designated calA through calH, for Calcofluor hypersensitivity. All cal mutants are impaired for sporulation at 30 C or 42 C or both, and in eight of the 10 mutations this sporulation defect shows at least partial osmotic remediability. All cal mutants show elevated sensitivity to one or more of the following agents: Caspofungin, Nikkomycin, Tunicamycin, Congo red and SDS, which are recognized wall-compromising agents or have been shown to be inhibitory to wall integrity mutants in yeast. Seven of the 10 cal mutants show swelling at elevated temperature, which in most cases is osmotically remediable. Spore swelling also can be induced at 30 C in all but one of the cal mutants by germination in the presence of one or more of the following: Caspofungin, Nikkomycin or Tunicamycin. Analysis of wall sugars showed no major changes in mutant strains. We also report that the chitin synthase inhibitor Nikkomycin induces excessive spore swelling during germination in all tested strains that have wild type cell wall metabolism (GR5, A4, A28 and AH12) at 42 C but not at 30 C. This effect mimics that of certain temperature-sensitive swollen cell (swo) mutations.

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“…CsmA in the hyphal tip might also be involved in maintaining cell wall integrity, because lysis in the subapical region and the formation of balloons, both of which were suppressed to some extent with osmotic stabilizers, were observed in the ⌬csmA null mutants; moreover, the amount of csmA mRNA became abundant under low osmotic conditions (Takeshita et al, 2002). It has also been suggested that CsmA functions in the maintenance of the cell wall in the chsA chsC double mutant (Yamada et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

CsmA, a Class V Chitin Synthase with a Myosin Motor-like Domain, Is Localized through Direct Interaction with the Actin Cytoskeleton inAspergillus nidulans

Takeshita

Ohta

Horiuchi

2005

MBoC

Self Cite

108

118

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One of the essential features of fungal morphogenesis is the polarized synthesis of cell wall components such as chitin. The actin cytoskeleton provides the structural basis for cell polarity in Aspergillus nidulans, as well as in most other eukaryotes. A class V chitin synthase, CsmA, which contains a myosin motor-like domain (MMD), is conserved among most filamentous fungi. The ⌬csmA null mutant showed remarkable abnormalities with respect to cell wall integrity and the establishment of polarity. In this study, we demonstrated that CsmA tagged with 9؋ HA epitopes localized near actin structures at the hyphal tips and septation sites and that its MMD was able to bind to actin. Characterization of mutants bearing a point mutation or deletion in the MMD suggests that the interaction between the MMD and actin is not only necessary for the proper localization of CsmA, but also for CsmA function. Thus, the finding of a direct interaction between the chitin synthase and the actin cytoskeleton provides new insight into the mechanisms of polarized cell wall synthesis and fungal morphogenesis. INTRODUCTIONThe filamentous fungus Aspergillus nidulans grows by generating ordered networks of filaments, or hyphae, which form a mycelium. Chitin, a ␤-1,4-linked homopolymer of N-acetylglucosamine (GlcNAc), is one of the major structural components of the fungal cell wall. The temporal and spatial regulation of its metabolism is very important for tip growth and the morphogenesis of a number of filamentous fungi (Bulawa, 1993;Cid et al., 1995). Actin is concentrated at the growing apices and sites of septum formation, where cell wall synthesis or septal synthesis is active (Harris et al., 1994;Momany and Hamer, 1997). Cytochalasin A, an inhibitor of actin polymerization, has been shown to induce the swelling of the hyphal tips and to block septum formation (Harris et al., 1994;Torralba et al., 1998). Thus, the actin cytoskeleton plays important roles in the determination of hyphal polarity (Torralba and Heath, 2001). Chitin synthases, membranebound proteins that catalyze the polymerization of GlcNAc from UDP-GlcNAc as a substrate, have been classified into at least six groups, classes I to VI, on the basis of the structures of their conserved region (Roncero, 2002). We have isolated five chitin synthase genes from A. nidulans and designated them as chsA, chsB, chsC, chsD, and csmA, and their gene products belong to classes II, III, I, IV, and V, respectively (Motoyama et al., 1994(Motoyama et al., , 1996Yanai et al., 1994;Fujiwara et al., 1997). The csmA (chitin synthase with a myosin motor-like domain) gene encodes a protein (1852 amino acids) consisting of an N-terminal myosin motor-like domain (MMD, ϳ800 amino acids) and a C-terminal chitin synthase domain (CSD, ϳ750 amino acids). Myosins are known as mechanoenzymes that convert chemical energy, liberated through ATP hydrolysis, into a mechanical force that is directed along actin filaments. The MMD of CsmA bears some consensus motifs of myosins, such as P-loop, Switch I, and...

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The Class V Chitin Synthase GenecsmAIs Crucial for the Growth of thechsA chsCDouble Mutant inAspergillus nidulans

Cited by 26 publications

References 28 publications

Polar Localizing Class V Myosin Chitin Synthases Are Essential during Early Plant Infection in the Plant Pathogenic FungusUstilago maydis

Polar Localizing Class V Myosin Chitin Synthases Are Essential during Early Plant Infection in the Plant Pathogenic FungusUstilago maydis

Isolation of cell wall mutants in Aspergillus nidulans by screening for hypersensitivity to Calcofluor White

CsmA, a Class V Chitin Synthase with a Myosin Motor-like Domain, Is Localized through Direct Interaction with the Actin Cytoskeleton inAspergillus nidulans

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