Date of Award
Doctor of Philosophy
The cells of Ustilago violacea, the anther smut fungus, extrude numerous hair-like appendages termed fimbriae. They have been shown to be similar to bacterial pili in that they are flexuous, proteinaceous fibrils, having a helical structure, a diameter of 7 nm and a variable length--often exceeding 15 (mu)m. Fimbriae were removed from cells by mechanical or thermal means. The isolated fimbriae were (a) chemically characterized; (b) injected into rabbits to obtain an antifimbrial antiserum (=AU). Fimbriae were found to consist of protein subunits of 74,000 daltons molecular weight with no detectable carbohydrate moiety. The protein was found to reassociate readily into fibrils of normal dimensions upon dialysis, and the reassociated fimbriae could be reattached to cells. Fimbrial protein was very resistant to thermal, or chemical treatments, maintaining both structural and antigenic integrity. The size of the fimbrial gene was estimated by UV mapping to be 2270 base pairs, only 17% larger than the 1944 base pairs needed to code for a 74,000 dalton protein. The antiserum AU agglutinated fimbriated but not defimbriated cells and was used as a test for the presence of fimbriae.;The presence of fimbriae on other fungi was examined by both direct EM observation and by serological screening for antigens responding to AU and to a similar antiserum raised against the fimbriae of Rhodotorula rubra. Visible fibrils resembling the fimbriae of U. violacea were seen on all tested smut fungi, with one exception, and on most basidiomycetous yeasts. Much shorter fibrils of similar diameter (6-10 nm) were observed on the surface of virtually all tested non-basidiomycetous fungi. Agglutination and immunofluorescence tests confirmed that the vast majority of the tested fungi possessed surface antigens which reacted with either one or both antisera.;It is concluded that fimbrial proteins are present on the surfaces of most fungi, rather than being restricted to smut fungi. It appears that the protein involved is highly conserved, though some differences in the antigenic region were detected. The possible functions of such fimbrial proteins are discussed.
Gardiner, Richard Buchanan, "Fungal Fimbriae: Their Structure And Distribution" (1985). Digitized Theses. 1411.