MOLECULAR-CLONING OF THE LECTIN AND A LECTIN-RELATED PROTEIN FROM COMMON SOLOMONS SEAL (POLYGONATUM-MULTIFLORUM)

The most prominent protein of Polygonatum multiflorum (common Solomon' s seal) rhizomes has been identified as a mannose-binding lectin. Anal ysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfa mily of monocot mannose-binding proteins. Screening of cDNA libraries constructed with RNA isolated from buds, leaves and flowers of P. mult iflorum also yielded cDNA clones encoding a protein, which contains tw o tandemly arranged domains with an obvious sequence homology to the m annose-binding lectins. Molecular modelling of the Polygonatum lectin and lectin-related protein indicated that the three-dimensional struct ure of both proteins strongly resembles that of the snowdrop lectin. I n addition, this approach suggested that the presumed carbohydrate-bin ding sites of the lectin can accommodate a mannose residue whereas mos t of the carbohydrate-binding sites of the lectin-related protein cann ot.