Expression and Regulation of Melanin Biosynthetic Genes during Appressorium Formation of Colletotrichum Lagenarium

Kubo, Yasuyuki; Takano, Yoshitaka; Tsuji, Gento; Kenmochi, Y.; Kuroda, Itaru; Horino, Osamu; Furusawa, Iwao

doi:10.1007/978-94-011-5218-1_28

Cited by 15 publications

(18 citation statements)

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“…Cloning of these three genes in C. lagenarium was also reported (28,39,44). However, in contrast to A. alternata it appears that these same genes are not closely linked in C. lagenarium (27). In M. grisea, classical genetic analysis with melanin mutants indicates none of the pathway genes are closely linked (10).…”

Section: Vol 69 2001mentioning

confidence: 88%

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Molecular Cloning and Characterization of WdPKS1 , a Gene Involved in Dihydroxynaphthalene Melanin Biosynthesis and Virulence in Wangiella ( Exophiala ) dermatitidis

et al. 2001

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1,8-Dihydroxynaphthalene (1,8-DHN) is a fungal polyketide that contributes to virulence when polymerized to 1,8-DHN melanin in the cell walls of Wangiella dermatitidis, an agent of phaeohyphomycosis in humans.To begin a genetic analysis of the initial synthetic steps leading to 1,8-DHN melanin biosynthesis, a 772-bp PCR product was amplified from genomic DNA using primers based on conserved regions of fungal polyketide synthases (Pks) known to produce the first cyclized 1,8-DHN-melanin pathway intermediate, 1,3,6,8-tetrahydroxynaphthalene. The cloned PCR product was then used as a targeting sequence to disrupt the putative polyketide synthase gene, WdPKS1, in W. dermatitidis. The resulting wdpks1⌬ disruptants showed no morphological defects other than an albino phenotype and grew at the same rate as their black wild-type parent. Using a marker rescue approach, the intact WdPKS1 gene was then successfully recovered from two plasmids. The WdPKS1 gene was also isolated independently by complementation of the mel3 mutation in an albino mutant of W. dermatitidis using a cosmid library. Sequence analysis substantiated that WdPKS1 encoded a putative polyketide synthase (WdPks1p) in a single open reading frame consisting of three exons separated by two short introns. This conclusion was supported by the identification of highly conserved Pks domains for a ␤-ketoacyl synthase, an acetyl-malonyl transferase, two acyl carrier proteins, and a thioesterase in the deduced amino acid sequence. Studies using a neutrophil killing assay and a mouse acute-infection model confirmed that all wdpks1⌬ strains were less resistant to killing and less virulent, respectively, than their wild-type parent. Reconstitution of 1,8-DHN melanin biosynthesis in a wdpks1⌬ strain reestablished its resistance to killing by neutrophils and its ability to cause fatal mouse infections.The zoopathogenic fungus Wangiella (Exophiala) dermatitidis is one of many form species of the Fungi Imperfecti, which are darkly pigmented (dematiaceous) owing to the deposition of 1,8-dihydroxynaphthalene (1,8-DHN) melanin in their cell walls (22,45). This fungus has recently become better known as a paradigm for the causative agents of phaeohyphomycosis and other emerging dermatomycoses of humans, because of its increasing detection as a systemic pathogen in both immunocompetent and immunocompromised patients (34, 35). Moreover, because W. dermatitidis has a well-defined polymorphic nature and a well-characterized cell wall chemistry, it serves as an excellent model for the more than 100 other dematiaceous fungal pathogens of humans (14,37,42).Although dark pigments of fungi are often called melanin without regard to mode of enzymatic synthesis or chemical composition, most syntheses of melanin are attributed to either a phenoloxidase, e.g., laccases and tyrosinases, or a polyketide synthase (Pks) of a pentaketide biosynthetic pathway (52). The phenoloxidases have been found mostly among basidiomycete fungi and are usually composed of soluble enzymes with broad substra...

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Section: Vol 69 2001mentioning

confidence: 88%

“…In the plant pathogenic fungi C. lagenarium and M. grisea, deficient 1,8-DHN melanin biosynthesis resulted in nonmelanized appressoria (27,32,39). In both cases, those mutants lost their ability to penetrate plant leaf tissue and thus became avirulent due to the fact that melanin is required for the rigidity of appressoria (2).…”

Section: Vol 69 2001mentioning

confidence: 99%

Molecular Cloning and Characterization of WdPKS1 , a Gene Involved in Dihydroxynaphthalene Melanin Biosynthesis and Virulence in Wangiella ( Exophiala ) dermatitidis

et al. 2001

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“…Melanin is required for full virulence in Cryptococcus, and melanized Cryptococcus cells are found in infected host tissues (8,(14)(15)(16)(17). Many phytopathogenic fungi, such as Colletotrichum lagenarium, Colletotrichum lindemuthianum, and Magnaporthe grisea, require melanized appressoria to penetrate host cells (18)(19)(20).…”

mentioning

confidence: 99%

Laccases Involved in 1,8-Dihydroxynaphthalene Melanin Biosynthesis in Aspergillus fumigatus Are Regulated by Developmental Factors and Copper Homeostasis

2013

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Aspergillus fumigatus produces heavily melanized infectious conidia. The conidial melanin is associated with fungal virulence and resistance to various environmental stresses. This 1,8-dihydroxynaphthalene (DHN) melanin is synthesized by enzymes encoded in a gene cluster in A. fumigatus, including two laccases, Abr1 and Abr2. Although this gene cluster is not conserved in all aspergilli, laccases are critical for melanization in all species examined. Here we show that the expression of A. fumigatus laccases Abr1/2 is upregulated upon hyphal competency and drastically increased during conidiation. The Abr1 protein is localized at the surface of stalks and conidiophores, but not in young hyphae, consistent with the gene expression pattern and its predicted role. The induction of Abr1/2 upon hyphal competency is controlled by BrlA, the master regulator of conidiophore development, and is responsive to the copper level in the medium. We identified a developmentally regulated putative copper transporter, CtpA, and found that CtpA is critical for conidial melanization under copper-limiting conditions. Accordingly, disruption of CtpA enhanced the induction of abr1 and abr2, a response similar to that induced by copper starvation. Furthermore, nonpigmented ctpA⌬ conidia elicited much stronger immune responses from the infected invertebrate host Galleria mellonella than the pigmented ctpA⌬ or wild-type conidia. Such enhancement in eliciting Galleria immune responses was independent of the ctpA⌬ conidial viability, as previously observed for the DHN melanin mutants. Taken together, our findings indicate that both copper homeostasis and developmental regulators control melanin biosynthesis, which affects conidial surface properties that shape the interaction between this pathogen and its host.A spergillus fumigatus is an opportunistic pathogen that causes life-threatening invasive disease in immunocompromised hosts (1). Its asexual spores, named conidia, are the initial source of inocula for infection and are the vehicles for dispersal and survival. Under favorable conditions, conidia break dormancy and grow as elongated, highly polarized hyaline hyphae. Upon achieving competency and exposure to air, hyphae produce aerial conidiophore stalks and develop elaborate multicellular conidiophores that generate chains of melanized uninucleate conidia (2, 3) (Fig. 1A and B). BrlA, a C 2 H 2 zinc finger transcription factor, is the master regulator that controls the initiation of conidiophore development in Aspergillus (4, 5). AbaA and WetA, two other important regulators that function downstream of BrlA, are required for proper progression of conidiation (6). The abaA gene is activated during the middle stage of conidiophore development, while the wetA gene is required for the activation of late conidiation-specific genes.The 1,8-dihydroxynaphthalene (DHN) melanin coating A. fumigatus conidia gives them their characteristic bluish green color (Fig. 1B). Melanin is an amorphous polymer that is produced by a variety of microbes and ...

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“…An association of melanin with pathogenicity has also been reported in other pathogens, such as Magnaporthe grisea and Colletotrichum lagenarium (Kubo et al, 2000). However, there are no reports accounting for a relationship between pigmentation and pathogenicity in S. sclerotiorum.…”

Section: Multiple Genetic Changes Associated With Gain Of Virulencementioning

confidence: 94%

Case Study: Sclerotinia sclerotiorum: Genetic Diversity and Disease Control

Petrofeza¹,

Nasser²

2012

The Molecular Basis of Plant Genetic Diversity

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Expression and Regulation of Melanin Biosynthetic Genes during Appressorium Formation of Colletotrichum Lagenarium

Cited by 15 publications

References 15 publications

Molecular Cloning and Characterization of WdPKS1 , a Gene Involved in Dihydroxynaphthalene Melanin Biosynthesis and Virulence in Wangiella ( Exophiala ) dermatitidis

Molecular Cloning and Characterization of WdPKS1 , a Gene Involved in Dihydroxynaphthalene Melanin Biosynthesis and Virulence in Wangiella ( Exophiala ) dermatitidis

Laccases Involved in 1,8-Dihydroxynaphthalene Melanin Biosynthesis in Aspergillus fumigatus Are Regulated by Developmental Factors and Copper Homeostasis

Case Study: Sclerotinia sclerotiorum: Genetic Diversity and Disease Control

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