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 Hydrophobins are expressed at different stages of fungal life › Ranging from vegetative hyphae and sporulating cultures to the fruiting bodies  Commonly found as structural proteins located on surfaces of aerial structures

 Hydrophobins are low molecular weight  Help fungi survive and adapt to proteins produced by filamentous fungi environment › They are amphiphiles – having hydrophobic › Important functional feature is the ability to and hydrophilic parts lower surface tension › Among the most surface active proteins  Various structural roles known  Physiological Role › Characteristic pattern of 8 cysteine residues › Mediate attachment to host during fungal that form four disulfide bonds infection

 Wessel and coworkers  Wessel concluded physical properties › Coined the term hydrophobins revealed two classes › Genetic studies of mushrooms like fungus, › Class I Schizophyllum commune  Form highly insoluble polymers › Studying transcriptome (mRNA profiles) in  Appearance of distinct rodlets mono- & dikaryotic strains of S. commune › Class II › Studying up-regulated genes during fruit  Form polymers that are soluble in some body formation organic solvents  Lack rodlet appearance

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 Made of about 100 amino acids  First studies of hydrophobins were made › Including 8 cysteine residues that allow the with mutant strains protein to fold resulting in a highly › Initial Observations hydrophobic domain  Ability to grow towards air  When react with air, turn into a  Interaction of pathogenic fungi with the host hydrophobic film that coats hyphae & plants may allow for interactions between  Additional studies have shown that similar hyphae proteins in other types of fungi have similar properties & structures

 Hydrophobins can be found in the  The presence of the eight cysteine (Cys) media in liquid fungal cultures residues:  Assemble on fungal cell walls A. Acts as sulfur substrate for amino acid like, like methionine  Cover fungal spores B. Is to form four (4) disulfide bonds  Coat surface and air cavities in fruiting C. Forms a polar region in protein bodies D. Forms non-polar region in protein

 What is the main role of hydrophobins?  Hydrophobins fold differs from any other A. To decrease surface tension analyzed protein B. To increase surface tension  Central Beta structure represents it C. To interact with other fungal cells hyrophobicity D. To regulate expression of housekeeping  Patch difference between class I and II genes

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 70 unique gene sequences found in databases  Found in fungi capable of hyphal growth › filamentous fungi › dimorphic yeast  More than 1 hydrophobin is present in 1 species

 Disulfides › Previous studies  Structural importance of disulfides and cys forms  Filamentous fungi seem to produce hydrophobins

 Prevents water logging  Cause changes in the properties of the › Create surface films that make the solid cell wall surfaces that hydrophobins bind to › Act as surfactants and reduce surface hydrophobic tension of growth medium › Spores of aerial structures are coated by › Allows fungi to breach air-water interface amphipathic layer, makes hydrophobic allowing the fungi to produce aerial resisting wetting and aiding air dispersal structures

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  Symbiotic Hydrophobins have been shown to be relationships highly expressed in ectomycorrhizal fungi › May be responsible for maintaining gas  Plant pathogens Mycorrizae spaces for

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 Rice blast fungus, Magnaporthe grisea  Chestnut blight fungus, Cryphonectria › MPG-1 knockout resulted in reduced parasitica appresorrium formation › Hydrophobins have been shown to be › MHP-1 has been shown to be highly important for stromal pustule eruption expressed during conidiation and pathogenesis.  Dutch elm disease, Ophistroma ulmi › Hydrophobins act as plant toxins and are not required for pathogenicity

http://ec.asm.org/cgi/content/full/4/5/931/F4

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 Barley pathogens: Fusarium and  What is not a significant advantage of Nigrospora species hydrophobins for the survival of fungi? › Causes beer gushing when added to beer a) Protects against desiccation bottles in microgram quantities b) Protects against wetting c) Aids in dispersal of spores d) Prevents gas exchange  True or False. Hydrophobins are required for pathogenicity in all fungi.

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