Circular dichroism analysis of the interaction between the alpha and beta subunits in a killer toxin produced by a halotolerant yeast, Pichia farinosa

SMK toxin is a killer toxin produced by a halotolerant yeast, Pichia farinosa. It is a heterodimer consisting of alpha (63 aa) and beta (77 aa) subunits, between which no disulfide bond exists. The two subunits interact tightly with each other below pH 5. However, the subunits dissociate under neutr...

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Bibliographic Details
Published in:Protein engineering 1997-02, Vol.10 (2), p.99-101
Main Authors: Suzuki, C, Kashiwagi, T, Tsuchiya, F, Kunishima, N, Morikawa, K, Nikkuni, S, Arata, Y
Format: Article
Language:English
Subjects:
Binding Sites
Circular Dichroism
Hydrogen-Ion Concentration
Killer Factors, Yeast
Models, Molecular
Molecular Structure
Mycotoxins - chemistry
Pichia - chemistry
Protein Conformation
Protein Engineering
Protein Structure, Secondary
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Summary:SMK toxin is a killer toxin produced by a halotolerant yeast, Pichia farinosa. It is a heterodimer consisting of alpha (63 aa) and beta (77 aa) subunits, between which no disulfide bond exists. The two subunits interact tightly with each other below pH 5. However, the subunits dissociate under neutral conditions, resulting in the aggregation of the alpha subunit and the concomitant loss of killer activity. CD spectral measurements showed that the secondary structure of the SMK toxin changes drastically in the pH range 5.1-5.5 and that after the dissociation of the subunits, the soluble beta subunit alone cannot take any secondary structure. It was also shown that the concentration of NaCl does not affect the secondary structure of the SMK toxin.
ISSN:0269-2139
1741-0126
1741-0134
DOI:10.1093/protein/10.2.99