title: Circular dichroism analysis of the interaction between the alpha and beta subunits in a killer toxin produced by a halotolerant yeast, Pichia farinosa.
abstract: 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.
authors.affiliation: National Food Research Institute, Tsukuba-shi, Ibaraki.
authors.forename: C
authors.initials: C
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Kashiwagi
authors.forename: F
authors.initials: F
authors.lastname: Tsuchiya
authors.forename: N
authors.initials: N
authors.lastname: Kunishima
authors.forename: K
authors.initials: K
authors.lastname: Morikawa
authors.forename: S
authors.initials: S
authors.lastname: Nikkuni
authors.forename: Y
authors.initials: Y
authors.lastname: Arata
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D055646:Killer Factors, Yeast; D008958:Models, Molecular; D015394:Molecular Structure; D009183:Mycotoxins / Q000737:chemistry*; D010843:Pichia / Q000737:chemistry*; D011487:Protein Conformation; D015202:Protein Engineering; D017433:Protein Structure, Secondary
chemical_list: D055646:Killer Factors, Yeast; D009183:Mycotoxins