cDNA cloning and 1.75 Aa crystal structure determination of PPL2, an endochitinase and N-acetylglucosamine-binding hemagglutinin from Parkia platycephala seeds

• Published in: The FEBS journal 2006-09, Vol.273 (17), p.3962-3974
• Main Authors: Cavada, Benildo S, Moreno, Frederico BB, da Rocha, Bruno AM, de Azevedo, Walter F, Castellon, Rolando ER, Goersch, Georg V, Nagano, Celso S, de Souza, Emmanuel P, Nascimento, Kyria S, Radis-Baptista, Gandhi, Delatorre, Plinio, Leroy, Yves, Toyama, Marcos H, Pinto, Vicente PT, Sampaio, Alexandre H, Barettino, Domingo, Debray, Henri, Calvete, Juan J, Sanz, Libia
• Format: Article
• Language: English
• Subjects: Mimosoideae; Parkia
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2006.05400.x

Parkia platycephala lectin 2 was purified from Parkia platycephala (Leguminosae, Mimosoideae) seeds by affinity chromatography and RP-HPLC. Equilibrium sedimentation and MS showed that Parkia platycephala lectin 2 is a nonglycosylated monomeric protein of molecular mass 29 407 plus or minus 15 Da, which contains six cysteine residues engaged in the formation of three intramolecular disulfide bonds. Parkia platycephala lectin 2 agglutinated rabbit erythrocytes, and this activity was specifically inhibited by N-acetylglucosamine. In addition, Parkia platycephala lectin 2 hydrolyzed beta (1-4) glycosidic bonds linking 2-acetoamido-2-deoxy- beta -d-glucopyranose units in chitin. The full-length amino acid sequence of Parkia platycephala lectin 2, determined by N-terminal sequencing and cDNA cloning, and its three-dimensional structure, established by X-ray crystallography at 1.75 Aa resolution, showed that Parkia platycephala lectin 2 is homologous to endochitinases of the glycosyl hydrolase family 18, which share the ( beta alpha ) sub(8) barrel topology harboring the catalytic residues Asp125, Glu127, and Tyr182.