Involvement of cell wall beta-glucan in the action of HM-1 killer toxin.
HM-1 killer toxin secreted from Hansenula mrakii inhibits the growth of Saccharomyces cerevisiae cells by interfering with beta-1,3-glucan synthesis. We found that HM-1 killer toxin killed intact cells but not protoplasts. In addition, cells lacking the functional KRE6 allele (kre6 delta) became resistant to higher concentration of HM-1 killer toxin. As reported by Roemer and Bussey [(1991) Proc. Natl. Acad. Sci. 88 11295-11299], cells lacking functional KRE6 had a reduced level of the cell wall beta-1,6-glucan compared to that in cells harboring the normal KRE6. These results suggest that the cell wall beta-glucan is involved in the action of HM-1 killer toxin. Addition of HM-1 killer toxin with several kinds of oligosaccharides revealed that either beta-1,3- or beta-1,6-glucan blocked the cytocidal action of HM-1 killer toxin whereas alpha-1,4-glucan and chitin did not. Mannan also interfered with HM-1 killer toxin action, but this inhibitory effect was much weaker than that observed with beta-1,3- or beta-1,6-glucans. Thus, it appears that the cell wall beta-glucan interacts with HM-1 killer toxin, and that this toxin-beta-glucan commitment is required for the action of HM-1 killer toxin.
Department of Mycology and Molecular Genetics, Nippon Roche Research Center, Kanagawa, Japan.
S
S
Kasahara
S
S
Ben Inoue
T
T
Mio
T
T
Yamada
T
T
Nakajima
E
E
Ichishima
Y
Y
Furuichi
H
H
Yamada
D002473:Cell Wall / Q000187:drug effects; D004352:Drug Resistance, Microbial; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D005936:Glucans; D055646:Killer Factors, Yeast; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D009154:Mutation; D009183:Mycotoxins / Q000494:pharmacology*; D010843:Pichia / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects*; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans
D005656:Fungal Proteins; D005936:Glucans; C081933:KRE6 protein, S cerevisiae; D055646:Killer Factors, Yeast; D008565:Membrane Proteins; D009183:Mycotoxins; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans; C064197:beta-1,6-glucan; C033363:beta-1,3-glucan