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Genomics-driven discovery of the pneumocandin biosynthetic gene cluster in the fungus Glarea lozoyensis.

Chen L, Yue Q, Zhang X, Xiang M, Wang C, Li S, Che Y, Ortiz-López FJ, Bills GF, Liu X, An Z - BMC Genomics (2013)

Bottom Line: Thus, the pneumocandin biosynthetic gene cluster is significantly more autonomous and organized than that of the recently characterized echinocandin B gene cluster.Characterization of the gene cluster provides a blueprint for engineering new pneumocandin derivatives with improved pharmacological properties.Whole genome estimation of the secondary metabolite-encoding genes from G. lozoyensis provides yet another example of the huge potential for drug discovery from natural products from the fungal kingdom.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.

ABSTRACT

Background: The antifungal therapy caspofungin is a semi-synthetic derivative of pneumocandin B0, a lipohexapeptide produced by the fungus Glarea lozoyensis, and was the first member of the echinocandin class approved for human therapy. The nonribosomal peptide synthetase (NRPS)-polyketide synthases (PKS) gene cluster responsible for pneumocandin biosynthesis from G. lozoyensis has not been elucidated to date. In this study, we report the elucidation of the pneumocandin biosynthetic gene cluster by whole genome sequencing of the G. lozoyensis wild-type strain ATCC 20868.

Results: The pneumocandin biosynthetic gene cluster contains a NRPS (GLNRPS4) and a PKS (GLPKS4) arranged in tandem, two cytochrome P450 monooxygenases, seven other modifying enzymes, and genes for L-homotyrosine biosynthesis, a component of the peptide core. Thus, the pneumocandin biosynthetic gene cluster is significantly more autonomous and organized than that of the recently characterized echinocandin B gene cluster. Disruption mutants of GLNRPS4 and GLPKS4 no longer produced the pneumocandins (A0 and B0), and the Δglnrps4 and Δglpks4 mutants lost antifungal activity against the human pathogenic fungus Candida albicans. In addition to pneumocandins, the G. lozoyensis genome encodes a rich repertoire of natural product-encoding genes including 24 PKSs, six NRPSs, five PKS-NRPS hybrids, two dimethylallyl tryptophan synthases, and 14 terpene synthases.

Conclusions: Characterization of the gene cluster provides a blueprint for engineering new pneumocandin derivatives with improved pharmacological properties. Whole genome estimation of the secondary metabolite-encoding genes from G. lozoyensis provides yet another example of the huge potential for drug discovery from natural products from the fungal kingdom.

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Pneumocandin structures and morphology of Glarea lozoyensis. (a) Chemical structures of pneumocandins. (b) Colony of G. lozoyensis on malt yeast agar (left panel); conidiophores and conidia of G. lozoyensis (right panels).
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Figure 1: Pneumocandin structures and morphology of Glarea lozoyensis. (a) Chemical structures of pneumocandins. (b) Colony of G. lozoyensis on malt yeast agar (left panel); conidiophores and conidia of G. lozoyensis (right panels).

Mentions: Fungi frequently cause deadly infections in immunocompromised patients resulting from HIV infection, cancer chemotherapy, and organ transplantation [1]. Until the introduction of caspofungin (CANCIDAS™) in 2001, antifungal therapy was limited to the use of polyenes (amphotericin B), azoles, and flucytosine which have high failure rates during management of fungal infection, while experiencing increasing clinical resistance [1]. The echinocandins are a class of antifungal lipopeptides targeting fungi via noncompetitive inhibition of the β-1,3-d-glucan synthase enzyme complex, leading to glucan polymer depletion in the fungal cell wall and resulting in osmotic instability and fungal cell lysis [1]. Human side effects to these chemicals are minimal because the target is absent in mammalian cells, and low dosing is used due to the drug’s potent efficacy [1,2]. Thus far, three echinocandin-based agents have been approved for clinical use [1]. Caspofungin, a semi-synthetic derivative of pneumocandin B0 (Figure 1a) which is a lipohexapeptide produced by the filamentous fungus Glarea lozoyensis (Figure 1b), was the first member of this class approved for human therapy; its registration was followed by micafungin (MYCAMINE™) derived from FR901370 (WF11899A), a sulfonated hexapeptide produced by the fungus Coleophoma empetri[3], and lastly anidulafungin (ERAXIS™) derived from echinocandin B produced by the fungus Aspergillus rugulosus[4]. The three fungal metabolites share a common chemical structure of cyclic lipohexapeptide with N-acylated to either 10,12-dimethylmyristoyl (pneumocandins) or palmitoyl (FR901370) or linoleoyl (echinocandin B); their hexapeptide cores differ from each other by modifications on 4-hydroxyproline or dihydroxyhomotyrosine (FR901370 and pneumocandins possess 3-hydroxyglutamine, while echinocandin B has threonine substituted in the same position) [5-8]. Because of their high efficacy, they have become the first-line therapy for the treatment of invasive fungal infections [1].


Genomics-driven discovery of the pneumocandin biosynthetic gene cluster in the fungus Glarea lozoyensis.

Chen L, Yue Q, Zhang X, Xiang M, Wang C, Li S, Che Y, Ortiz-López FJ, Bills GF, Liu X, An Z - BMC Genomics (2013)

Pneumocandin structures and morphology of Glarea lozoyensis. (a) Chemical structures of pneumocandins. (b) Colony of G. lozoyensis on malt yeast agar (left panel); conidiophores and conidia of G. lozoyensis (right panels).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672099&req=5

Figure 1: Pneumocandin structures and morphology of Glarea lozoyensis. (a) Chemical structures of pneumocandins. (b) Colony of G. lozoyensis on malt yeast agar (left panel); conidiophores and conidia of G. lozoyensis (right panels).
Mentions: Fungi frequently cause deadly infections in immunocompromised patients resulting from HIV infection, cancer chemotherapy, and organ transplantation [1]. Until the introduction of caspofungin (CANCIDAS™) in 2001, antifungal therapy was limited to the use of polyenes (amphotericin B), azoles, and flucytosine which have high failure rates during management of fungal infection, while experiencing increasing clinical resistance [1]. The echinocandins are a class of antifungal lipopeptides targeting fungi via noncompetitive inhibition of the β-1,3-d-glucan synthase enzyme complex, leading to glucan polymer depletion in the fungal cell wall and resulting in osmotic instability and fungal cell lysis [1]. Human side effects to these chemicals are minimal because the target is absent in mammalian cells, and low dosing is used due to the drug’s potent efficacy [1,2]. Thus far, three echinocandin-based agents have been approved for clinical use [1]. Caspofungin, a semi-synthetic derivative of pneumocandin B0 (Figure 1a) which is a lipohexapeptide produced by the filamentous fungus Glarea lozoyensis (Figure 1b), was the first member of this class approved for human therapy; its registration was followed by micafungin (MYCAMINE™) derived from FR901370 (WF11899A), a sulfonated hexapeptide produced by the fungus Coleophoma empetri[3], and lastly anidulafungin (ERAXIS™) derived from echinocandin B produced by the fungus Aspergillus rugulosus[4]. The three fungal metabolites share a common chemical structure of cyclic lipohexapeptide with N-acylated to either 10,12-dimethylmyristoyl (pneumocandins) or palmitoyl (FR901370) or linoleoyl (echinocandin B); their hexapeptide cores differ from each other by modifications on 4-hydroxyproline or dihydroxyhomotyrosine (FR901370 and pneumocandins possess 3-hydroxyglutamine, while echinocandin B has threonine substituted in the same position) [5-8]. Because of their high efficacy, they have become the first-line therapy for the treatment of invasive fungal infections [1].

Bottom Line: Thus, the pneumocandin biosynthetic gene cluster is significantly more autonomous and organized than that of the recently characterized echinocandin B gene cluster.Characterization of the gene cluster provides a blueprint for engineering new pneumocandin derivatives with improved pharmacological properties.Whole genome estimation of the secondary metabolite-encoding genes from G. lozoyensis provides yet another example of the huge potential for drug discovery from natural products from the fungal kingdom.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.

ABSTRACT

Background: The antifungal therapy caspofungin is a semi-synthetic derivative of pneumocandin B0, a lipohexapeptide produced by the fungus Glarea lozoyensis, and was the first member of the echinocandin class approved for human therapy. The nonribosomal peptide synthetase (NRPS)-polyketide synthases (PKS) gene cluster responsible for pneumocandin biosynthesis from G. lozoyensis has not been elucidated to date. In this study, we report the elucidation of the pneumocandin biosynthetic gene cluster by whole genome sequencing of the G. lozoyensis wild-type strain ATCC 20868.

Results: The pneumocandin biosynthetic gene cluster contains a NRPS (GLNRPS4) and a PKS (GLPKS4) arranged in tandem, two cytochrome P450 monooxygenases, seven other modifying enzymes, and genes for L-homotyrosine biosynthesis, a component of the peptide core. Thus, the pneumocandin biosynthetic gene cluster is significantly more autonomous and organized than that of the recently characterized echinocandin B gene cluster. Disruption mutants of GLNRPS4 and GLPKS4 no longer produced the pneumocandins (A0 and B0), and the Δglnrps4 and Δglpks4 mutants lost antifungal activity against the human pathogenic fungus Candida albicans. In addition to pneumocandins, the G. lozoyensis genome encodes a rich repertoire of natural product-encoding genes including 24 PKSs, six NRPSs, five PKS-NRPS hybrids, two dimethylallyl tryptophan synthases, and 14 terpene synthases.

Conclusions: Characterization of the gene cluster provides a blueprint for engineering new pneumocandin derivatives with improved pharmacological properties. Whole genome estimation of the secondary metabolite-encoding genes from G. lozoyensis provides yet another example of the huge potential for drug discovery from natural products from the fungal kingdom.

Show MeSH
Related in: MedlinePlus