Fruit-specific lectins from banana and plantain

• Published in: Planta 2000-09, Vol.211 (4), p.546-554
• Main Authors: Peumans, Willy J., Zhang, Wenling, Barre, Annick, Astoul, Corinne Houlès, Balint-Kurti, Peter J., Rovira, Paula, Rougé, Pierre, May, Gregory D., Van Leuven, Fred, Truffa-Bachi, Paolo, Van Damme, Els J. M.
• Format: Article
• Language: English
• Subjects: Agglutination; Agglutinins; Agronomy. Soil science and plant productions; Amino Acid Sequence; Amino acids; Biological and medical sciences; Cell biochemistry; Cell physiology; Chemical constitution; Cloning, Molecular; Complementary DNA; Economic plant physiology; Fruit - chemistry; Fruit - classification; Fundamental and applied biological sciences. Psychology; Gels; Leaves; Lectins; Lectins - chemistry; Lectins - genetics; Lectins - isolation & purification; Molecular Sequence Data; Phylogeny; Plant Lectins; Plant physiology and development; Plants; Proteins; RNA; Sequence Homology, Amino Acid; Species Specificity
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250000307

One of the predominant proteins in the pulp of ripe bananas (Musa acuminata L.) and plantains (Musa spp.) has been identified as a lectin. The banana and plantain agglutinins (called BanLec and PlanLec, respectively) were purified in reasonable quantities using a novel isolation procedure, which prevented adsorption of the lectins onto insoluble endogenous polysaccharides. Both BanLec and PlanLec are dimeric proteins composed of two identical subunits of 15 kDa. They readily agglutinate rabbit erythrocytes and exhibit specificity towards mannose. Molecular cloning revealed that BanLec has sequence similarity to previously described lectins of the family of jacalin-related lectins, and according to molecular modelling studies has the same overall fold and three-dimensional structure. The identification of BanLec and PlanLec demonstrates the occurrence of jacalin-related lectins in monocot species, suggesting that these lectins are more wide-spread among higher plants than is actually believed. The banana and plantain lectins are also the first documented examples of jacalin-related lectins, which are abundantly present in the pulp of mature fruits but are apparently absent from other tissues. However, after treatment of intact plants with methyl jasmonate, BanLec is also clearly induced in leaves. The banana lectin is a powerful murine T-cell mitogen. The relevance of the mitogenicity of the banana lectin is discussed in terms of both the physiological role of the lectin and the impact on food safety.