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Hydrophobin Presentations 11/8/09 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 1 11/8/09 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 2 11/8/09 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 3 11/8/09 Symbiotic Hydrophobins have been shown to be relationships highly expressed in ectomycorrhizal fungi › May be responsible for maintaining gas Plant pathogens Mycorrizae spaces for http://images.google.com/imgres?imgurl=http:// www.apsnet.org/online/Archive/1-9.jpg h,p://www.greenmanconserva7on.co.uk/Images/Photos/Web %20Ready/Mycorrhiza/Roots.jpg h,p://www.greenmanconserva7on.co.uk/Images/Photos/ Web%20Ready/Mycorrhiza/Roots.jpg 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 4 11/8/09 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. h,p://www.crc.dk/flab/images/Image19.gif 5 .
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