The purification and characterization of an intracellular sex-specific mannan protein from yeast

Sexual behavior and its pheromonal regulation in ascosporogenous yeasts

We reviewed our investigations on sexual behaviors and interactions including sexual cell agglutination and pheromone action mainly in non-conventional yeasts, Hansenula anomala, H. wingei, Pichia amethionina, P. heedi, P. opuntiae, Saccharomyces kluyveri, S. globsus, S. exiguus, Saccharomycodes ludwigii. The techniques and genetic models including the cassette model and alpha 1-alpha 2 hypothesis which had been developed largely in S. cerevisiae were applicable to these yeasts in principle. The sexual agglutination was distinctly species-specific while sex pheromones were cross-reactive beyond species' barriers. The successful induction of heterothallic strains from homothallic strains in S. exiguus by mutagenesis enabled to the subsequent biochemical and genetical analysis of sexual behavior in the yeast. The phylogenetic consideration on sex differentiation is also included.

Attachment of SA-11 rotavirus to erythrocyte receptors

Treatment of human group O and sheep erythrocytes with receptor-destroying enzyme rendered them inagglutinable by simian rotavirus SA-11. The erythrocyte receptors were also removed by periodate oxidation and markedly reduced by incubation with a high concentration of trypsin, but they were not altered by infectivity-enhancing concentrations of trypsin, p-hydroxymercuribenzoate, or sodium sulfite (Na2SO3). Hemagglutinating activity of the virus particles was destroyed by periodate oxidation at 37 degrees C, p-hydroxymercuribenzoate, and a high concentration of trypsin and decreased by Na2SOa but was not altered by incubation with receptor-destroying enzyme, infectivity-enhancing concentrations of trypsin, or periodate oxidation at 4 degrees C. These results indicate that neuraminic acid-containing receptor substances are involved in the interaction of the virus with human and sheep erythrocytes, and suggest that SA-11-erythrocyte union involves carbohydrate on the surface of erythrocytes but not on the virion. Sensitivities of the SA-11 hemagglutinin to alcohols and repeated freeze-thaw cycles were also investigated.

Mating reaction in Saccharomyces cerevisiae. VIII. Mating-type-specific substances responsible for sexual cell agglutination

The agglutination factors of a and alpha mating types of Saccharomyces cerevisiae were solubilized from isolated cell-wall fractions by treatment with snail enzyme (Glusulase) and shown to be adsorbed specifically by cells of the opposite mating type, resulting in the loss of agglutinability of these cells. The agglutination factors of a and alpha types adsorbed by cells of the opposite mating type at pH 5.5 were eluted at pH 9.0. These factors were further purified on Sepharose 4B. From the elution pattern on Sepharose 4B, the molecular weights of the solubilized agglutination factors are estimated to be about one million. Thus purified agglutination factors contained carbohydrate and protein and were considerably resistant to heat treatment. Neutral protease of Bacillus subtilis inactivated both a and alpha type agglutination factors. Trypsin inactivated the alpha type agglutination factor only.

Mating reaction in Saccharomyces cerevisiae. VII. Effect of proteolytic enzymes on sexual agglutinability and isolation of crude sex-specific substances responsible for sexual agglutination

The effect of proteolytic enzymes on sexual agglutinability of haploid cells of the yeast Saccharomyces cerevisiae was examined. Sexual agglutinability of cells of both a and alpha types was lost on treatment with alkaline protease and two kinds of neutral proteases of Bacillus subtilis, pronase and alpha-chymotrypsin. Agglutinability of alpha type cells was lost after treatment with acid protease of Rhizopus chinensis and trypsin, but that of a type cells was not. These results indicate that the sex-specific substance responsible for the sexual agglutination (agglutination factor) in a type cells differ from that in alpha type cells. Agglutination factors were solubilized from cell-wall fractions of both mating types by Glusalase treatment. These crude factors specifically inhibited the agglutinability of cells of the opposite mating type with little effect on the agglutinability of cells of the same mating type.

Inhibition of transformation by sodium metaperiodate in Streptococcus sanguis (Wicky): demonstration that deoxyribonucleic acid binding sites contain amino acids

Addition of sodium metaperiodate to competent Streptococcus sanguis (Wicky) cells at 0 or 37 C revealed that the deoxyribonucleic acid binding sites consist of amino acids.

Molecular complementarity of yeast glycoprotein mating factors

Cell fusion between opposite mating types 5 and 21 of the yeast Hansenula wingei is initiated by a strong sexual agglutination reaction. The mating factors responsible for the specificity of cellular recognition are complementary glycoproteins which form a physical complex in vitro. The complex is assayed by recovery of agglutination activity of the multivalent 5-factor after the univalent 21-factor has been inactivated by treatment of the complex with alkali. The 5-factor.21-factor complex, purified on Sepharose 6B, is large (several million daltons) and heterogeneous. The three peaks of 5-factor activity contain a number of combining sites proportional to molecular size.

Molecular basis of mating in the yeast hansenula wingei

Images

Molecular aspects of specific cell contact

Complementary macromolecules were isolated from yeasts of opposite mating type. These cell-surface molecules neutralize each other as do antibodies and antigens. Both yeast factors are glycoproteins of low molecular weight. Other specific cell associations may be due to the interaction of such complementary macromolecules.