Bioinformatics predicts diverse Aspergillus hydrophobins with novel properties

Hydrophobins, small, amphipathic proteins found only in filamentous fungi, have the ability to form elastic layers at air/water or oil/water interfaces. To identify potentially useful hydrophobins for technological applications, a bioinformatics approach has been employed. The methodology used is not only useful for the identification of hydrophobins but, can be used for the identification of other structurally similar proteins that have little amino-acid homology. The Aspergillus comparative database initially revealed 25 officially annotated hydrophobins from a keyword search. A detailed manual annotation using Blast searches and multiple alignments showed common errors in assigning descriptions centred upon difficulties in recognising the relatively small conserved motif of four pairs of cysteines. Searches across the databases gave two protein sequences from the Central Aspergillus Data Repository (CADRE) and two from Uniprot which did not match to any found on the Aspergillus comparative database. A total of 74 putative hydrophobin sequences were found across the different databases. The number per species ranges from six for Aspergillus oryzae to ten for Aspergillus clavatus, Aspergillus fischeri, Aspergillus terreus, Aspergillus nidulans and Aspergillus niger. Possible examples of proteins which appear to be an intermediate form between Class I and II were found. It is thought that this intermediate form may be of most use for food applications as hopefully it will have amenable solubility and assembly kinetics to be used in standard food production operations. The applications of computer aided bioinformatics for the selection and development of hydrophobins for model production systems are discussed.