Crystallization and Preliminary X-Ray Crystallographic Analysis of Galectin LEC-1 from Caenorhabditis elegans

Galectin LEC-1 isolated from the nematode Caenorhabditis elegans was the first galectin found in invertebrates and also the first tandem-repeat-type galectin identified, containing two homologous carbohydrate-binding sites. This galectin is localized most abundantly in the adult cuticle and possibly plays a role in the formation of epidermal layers. We succeeded in crystallizing LEC-1 composed of 279 amino acids with a calculated molecular weight of 31,809 Da under two independent sets of conditions as a result of extensive screening. The crystals grown under one set of conditions belong to the triclinic space group P1, with unit-cell parameters a = 48.44, b = 52.13, c = 64.24 Å, α = 108.73, β = 91.39, and γ = 98.45 and two protein molecules per unit cell. The crystals grown under the other set of conditions which included lactose belong to the monoclinic space group P21, with unit-cell parameters a = 52.90, b = 47.01, c = 66.16 Å, and β = 113.30° and one protein molecule per asymmetric unit.