Morphogenetic effects induced by spermine and ruthenium red in yeasts

Spermine (Sp) produces growth inhibition and wall malformation in Saccharomyces cerevisiae in response to oversynthesis of beta-glucans and chitin. The effect is related to the polycation nature of the molecule. In the present work, to verify this hypothesis, the yeast was treated with the abiogenic polycation ruthenium red (RR). The strict analogy observed between the RR- and Sp-induced alterations reinforced our earlier assumption that Sp interacted with the anionic sites of the plasmalemma determining a spurious activation of the two inserted enzymes beta-glucan and chitin synthases. This view was further confirmed by the aberrant accumulation of beta-glucans in Schizosaccharomyces pombe and of chitin in Rhodotorula glutinis treated with Sp and RR. In these micro-organisms spermidine, which bears three amino groups instead of the four encountered in Sp, was ineffective. It is inferred that at least four cation sites must be present in a compound in order to affect wall morphogenesis in yeasts.