Seminalplasmin, an Antimicrobial Protein from Bull Seminal Plasma, Inhibits Growth, and Synthesis of Nucleic Acids and Proteins in S. cerevisiae

Abstract

Seminalplasmin, an antimicrobial protein present in bovine seminal plasma, is shown to inhibit the growth of, as well as nucleic acid and protein synthesis in, wild-type Saccharomyces cerevisiae SM202, when used at concentrations greater than 200 micrograms/ml, in contrast to 20 micrograms/ml that is sufficient for Escherichia coli. An osmotically labile strain of S. cerevisiae VY1160 is 1-2 orders of magnitude more sensitive to seminalplasmin than the wild-type strain. RNA synthesis in protoplasts and nuclei of S. cerevisiae SM 202 was also about as sensitive to seminalplasmin as in E. coli and S. cerevisiae VY1160. The RNA polymerases I and II from S. cerevisiae were strongly inhibited by seminalplasmin in vitro, while DNA and protein syntheses were not affected by seminalplasmin in cell-free systems, unlike in the whole cells. It is concluded that seminalplasmin acts in S. cerevisiae by entering the cells and inhibiting transcription.