Characterization of the velvet regulators in Aspergillus fumigatus

Authors

  • Hee-Soo Park,

    1. Department of Bacteriology, University of Wisconsin, Madison, WI, USA
    2. Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI, USA
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  • Özgür Bayram,

    1. Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
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  • Gerhard H. Braus,

    1. Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
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  • Sun Chang Kim,

    1. Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Dae-Jon, Korea
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  • Jae-Hyuk Yu

    Corresponding author
    1. Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI, USA
    2. Department of Genetics, University of Wisconsin, Madison, WI, USA
    • Department of Bacteriology, University of Wisconsin, Madison, WI, USA
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For correspondence. E-mail jyu1@wisc.edu; Tel. (+1) 608 262 4696; Fax (+1) 608 262 9865.

Summary

Fungal development and secondary metabolism is intimately associated via activities of the fungi-specific velvet family proteins. Here we characterize the four velvet regulators in the opportunistic human pathogen Aspergillus fumigatus. The deletion of AfuvosA, AfuveA and AfuvelB causes hyperactive asexual development (conidiation) and precocious and elevated accumulation of AfubrlA during developmental progression. Moreover, the absence of AfuvosA, AfuveA or AfuvelB results in the abundant formation of conidiophores and highly increased AfubrlA mRNA accumulation in liquid submerged culture, suggesting that they act as repressors of conidiation. The deletion of AfuvosA or AfuvelB causes a reduction in conidial trehalose amount, long-term spore viability, conidial tolerance to oxidative and UV stresses, and accelerated and elevated conidial germination regardless of the presence or absence of an external carbon source, suggesting an interdependent role of them in many aspects of fungal biology. Genetic studies suggest that AfuAbaA activates AfuvosA and AfuvelB expression during the mid to late phase of conidiation. Finally, the AfuveA null mutation can be fully complemented by Aspergillus nidulans VeA, which can physically interact with AfuVelB and AfuLaeA in vivo. A model depicting the similar yet different roles of the velvet regulators governing conidiation and sporogenesis in A. fumigatus is presented.

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