Received August 4, 2006
Accepted November 4, 2006
A Novel Family of Lectins Evolutionarily Related to Class V Chitinases. An Example of Neofunctionalization in Legumes
Els J.M. Van Damme *, Raphaël Culerrier , Annick Barre , Richard Alvarez , Pierre Rougé , and Willy J. Peumans
Department of Molecular Biotechnology, Lab. Biochemistry and Glycobiology, Ghent University, Coupure Links 653, 9000 Gent, Belgium
Surfaces cellulaires et Signalisation chez les Végétaux, UMR CNRS-UPS 5546, Pôle de Biotechnologies Végétales, 24 Chemin de Borde Rouge, B.P. 17, 31326 Castanet-Tolosan, France
Department of Biochemistry and Molecular Biology, University of Oklahoma, Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
* Corresponding author; email: ElsJM.VanDamme{at}UGent.be.
A lectin has been identified in the bark of black locust (Robinia pseudoacacia L.) bark that shares approximately 50% sequence identity with plant class V chitinases but is essentially devoid of chitinase activity. Specificity studies indicated that the Robinia pseudoacacia chitinase-related agglutinin or RobpsCRA preferentially binds to high mannose N-glycans comprising the proximal pentasaccharide core structure. Closely related orthologues of RobpsCRA could be identified in the legumes Glycine max, Medicago truncatula and Lotus japonicus but in no other plant species, suggesting that this novel lectin family most probably evolved in an ancient legume species or possibly an earlier ancestor. The present identification of RobpsCRA not only illustrates neofunctionalization in plants but also provides the first firm evidence that plants are capable of developing a sugar-binding domain from an existing structural scaffold with a different activity and accordingly sheds a new light on the molecular evolution of plant lectins.
