Structural highlights
Publication Abstract from PubMedTarin, the Colocasia esculenta lectin from the superfamily of alpha-d-mannose-specific plant bulb lectins, is a tetramer of 47 kDa composed of two heterodimers. Each heterodimer possesses homologous monomers of ~11.9 (A chain) and ~12.7 (B chain) kDa. The structures of apo and carbohydrate-bound tarin were solved to 1.7 A and 1.91 A, respectively. Each tarin monomer forms a canonical beta-prism II fold, common to all members of Galanthus nivalis agglutinin (GNA) family, which is partially stabilized by a disulfide bond and a conserved hydrophobic core. The heterodimer is formed through domain swapping involving the C-terminal beta-strand and the beta-sheet on face I of the prism. The tetramer is assembled through the dimerization of the B chains from heterodimers involving face II of each prism. The 1.91 A crystal structure of tarin bound to Manalpha(1,3)Manalpha(1,6)Man reveals an expanded carbohydrate-binding sequence (QxDxNxVxYx4/6WX) on face III of the beta-prism. Both monomers possess a similar fold, except for the length of the loop, which begins after the conserved tyrosine and creates the binding pocket for the alpha(1,6)-terminal mannose. This loop differs in size and amino-acid composition from 10 other beta-prism II domain proteins, and may confer carbohydrate-binding specificity among members of the GNA-related lectin family. High-resolution crystal structures of Colocasia esculenta tarin lectin.,Pereira PR, Meagher JL, Winter HC, Goldstein IJ, Paschoalin VM, Silva JT, Stuckey JA Glycobiology. 2016 Aug 24. PMID:27558840[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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