HCF-1, a hydrophobin from the tomato pathogen Cladosporium fulvum

Abstract

A hydrophobin, named HCF-1, was isolated from the culture medium of Cladosporium fulvum, the causal agent of tomato leaf mould. The protein forms insoluble aggregates when the medium is vigorously aerated. These aggregates can be dissociated by trifluoroacetic acid into monomers which migrate as 10-kDa molecules on SDS-PAGE. HCf-1 is encoded by a single gene, HCf-1. The gene contains two small introns and is translated into a 105-amino acid protein which is then processed to give a mature 83-amino acid protein. The position of the eight cysteine residues and the predicted hydrophobicity profile are typical of fungal hydrophobins. HCf-1 RNA is expressed in growing mycelium and conidia but its quantity diminishes transiently after germination; its abundance does not change when the fungus is grown on nitrogen- or carbon-deficient medium. This is the first step in evaluating the role of hydrophobins in establishment of basic compatibility between C. fulvum and tomato.