(16)-beta-D-glucan as the cell wall binding site for Debaryomyces hansenii killer toxin

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Abstract
Aims: The aims of this study were to characterize the cell wall binding site of Debaryomyces hansenii killer toxin to provide a simple purification method and to determine some characteristics of this toxin. Methods and Results: Various linear (1→6)-β-D-glucans of different origins were effective competitive inhibitors of the toxin action. Periodate oxidation and 1H-NMR was used to determine the receptor nature. Affinity chromatography on pustulan-Sepharose column was used to purify D. hansenii killer toxin, probably a 23-kDa protein. The killer toxin character was cureless. Conclusions: The investigation revealed that the killer toxin was mainly adsorbed by (1→6)-β-D-glucans. This is a low molecular weight protein, probably encoded by chromosomal genes. Significance and Impact of the Study: The specificity of the killer toxin for its receptor provides an effective means to purify the killer toxin. This study is the first to identify the cell wall binding site of this killer toxin, a toxin with properties of industrial relevance.