EFFECTS OF SPERMINE AND SPERMIDINE ON CELL-DIVISION AND WALL MORPHOGENESIS IN SACCHAROMYCES-CEREVISIAE

The effect of polyamines (PA) or the synthesis and deposition of wall constituents in Saccharomyces cerevisiae was investigated. Spermidine (Spd) in various doses was ineffective whereas spermine (Sp) in the sa me concentrations caused a marked inhibition (25-60%) of cell prolifer ation accompanied by evident morphogenetic malformations. Sp-treated c ells were elongated, grouped in small clusters, and showed malformed s epta and aberrant wall thickenings, The PATAg technique revealed that the aberrations consisted of an abnormal accumulation of both reactive materials, like 1, 3-beta-glucans, and unstained chitin components. S ince 1,3-beta-glucan synthases and chitin synthases are inserted in th e plasma membrane whose anionic sites interacted with the cation group s of Sp, it is assumed that the molecule determines a condition result ing in an unregulated activation of the two enzymes. The fact that Spd , which contains three cationic groups instead of the four contained i n Sp, is without effect suggests that a compound must have at least fo ur cation sites in order to affect the cell division and wall morphoge nesis of S. cerevisiae.