Fungal fimbriae. IV. Composition and properties of fimbriae from Ustilago violacea

Abstract

The fimbriae of Ustilago violacea consist of long protein fibrils of 7-nm diameter. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the fimbriae of this species and of several other species of Ustilago and Rhodotorula demonstrated that they are composed of a protein of 74, 000 Da which can spontaneously assemble into 7-nm fibrils. No carbohydrate moiety was detected. Fimbrial protein retained both its fibrillar structure and antigenicity when exposed to a variety of chemical treatments, and even when autoclaved. Concentrations of cations greater than 10 −1 M (monovalent cations) or 5 × 10 −2 M (divalent cations) resulted in a loss of fimbriae, while the effect of chelators suggested that calcium is important to the structural integrity of fimbriae. Ouchterlony tests using antisera prepared against the fimbriae of U. violacea and R. rubra indicated that while there are differences in the antigenic sites, the fimbrial protein of different basidiomycete species is highly conserved. Fimbrial protein did not react with several mammalian antisera directed against cytoskeletal proteins.