The amino-acid sequence of the glucose/mannose-specific lectin isolated from Parkia platycephala seeds reveals three tandemly arranged jacalin-related domains.
A mannose/glucose-specific lectin was isolated from seeds of Parkia platycephala, the most primitive subfamily of Leguminosae plants. The molecular mass of the purified lectin determined by mass spectrometry was 47 946 +/- 6 Da (by electrospray ionization) and 47 951 +/- 9 Da (by matrix-assisted laser-desoption ionization). The apparent molecular mass of the lectin in solutions of pH in the range 4.5-8.5 determined by analytical ultracentrifugation equilibrium sedimentation was 94 +/- 3 kDa, showing that the protein behaved as a non-pH-dependent dimer. The amino-acid sequence of the Parkia lectin was determined by Edman degradation of overlapping peptides. This is the first report of the primary structure of a Mimosoideae lectin. The protein contained a blocked N-terminus and a single, nonglycosylated polypeptide chain composed of three tandemly arranged homologous domains. Each of these domains shares sequence similarity with jacalin-related lectin monomers from Asteraceae, Convolvulaceae, Moraceae, Musaceae, Gramineae, and Fagaceae plant families. Based on this homology, we predict that each Parkia lectin repeat may display a beta prism fold similar to that observed in the crystal structure of the lectin from Helianthus tuberosus. The P. platycephala lectin also shows sequence similarity with stress- and pathogen-upregulated defence genes of a number of different plants, suggesting a common ancestry for jacalin-related lectins and inducible defence proteins.
Mann
K
K
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Farias
C M
CM
Del Sol
F G
FG
Santos
C F
CF
Grangeiro
T B
TB
Nagano
C S
CS
Cavada
B S
BS
Calvete
J J
JJ
D000595:Amino Acid Sequence; D007887:Fabaceae / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry*; D008969:Molecular Sequence Data; D037121:Plant Lectins; D010946:Plants, Medicinal; D020836:Protein Structure, Quaternary; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D014961:X-Ray Diffraction
D037102:Lectins; D037121:Plant Lectins