Round shape enlargement of the yeast spheroplast of Saccharomyces cerevisiae by HM-1 toxin.
The effects of HM-1 killer toxin (HM-1) on yeast spheroplasts of Saccharomyces cerevisiae were examined under osmotically stabilized conditions. Prolonged incubation of spheroplasts in nutrient-rich media resulted in an increase in volume, accompanied by aberrant morphological changes. By contrast, spheroplasts were enlarged, maintaining a round shape, when incubated in HM-1 media. The required 50% effective dose of HM-1 was as low as 2.2 x 10(-8) M, and this effect by HM-1 was specific to yeast sensitive to RM-1. Some parts of the enlarged spheroplasts were stable, but the round shape was deformed as HM-1 was removed from the medium. In both the control and HM-1-treated spheroplasts, the total protein and DNA content were increased by approximately three and four times in response to their incubations, respectively. Cytochemical analysis by 4'6-diamidino-2-phenylindol (DAPI) staining showed multiple nuclei. Consistently, actin patches of cells were evenly distributed in both the control and HM-1-treated spheroplasts. A similar enlargement of spheroplasts was observed with lipophilic antifungal compounds, aculeacin A and papulacandin B, but the effects were distinct from those of HM-1 because the spheroplasts resulted in lysis after a long incubation. The molecular mechanism(s) behind this unique observation remains to be studied, but it is clear that HM-1 is an excellent tool for studying yeast cell biology.
Department of Biochemistry, Niigata College of Pharmacy, Japan. tkomiyam@niigata-pharm.ac.jp
Tadazumi
T
Komiyama
Tetsuya
T
Kimura
Yasuhiro
Y
Furuichi
D048429:Cell Size / Q000187:drug effects; D055646:Killer Factors, Yeast; D009183:Mycotoxins / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects*; D013104:Spheroplasts / Q000166:cytology / Q000187:drug effects*
D055646:Killer Factors, Yeast; D009183:Mycotoxins