Isolation, crystallization, and characterization of a 16.5-kDa protein from fruit bodies of a lectin-deficient strain of Pleurotus cornucopiae.

Among mushrooms of Pleurotus cornucopiae two kinds of fruit bodies, lectin (PCL)-containing and -deficient, were found. The PCL-deficient fruit body was found to contain a 16.5-kDa protein, which was purified to homogeneity and crystallized. Properties of the protein were investigated in comparison with PCL. The protein consisted of four identical subunits each having a molecular mass of 16.5 kDa, which was close to that of PCL. Partial amino acid sequences of the two proteins were analyzed and some sequence homology was found, although the protein did not cross-react with anti-PCL serum and it was devoid of binding activity for mucin, an inhibitor of PCL. The 16.5-kDa protein was not found in vegetatively growing mycelia, indicating that the synthesis of the protein was developmentally regulated as was PCL. The results suggest that the 16.5-kDa protein was related to PCL.