Abstract

It is the aim of comparative structural biology to define the evolutionarily important traits of protein function and the points of diversification. Consequently, structural analysis, especially of distant members in a family which in this case are lectins involved in cell adhesion and growth regulation in animals (i.e. galectins), is required. For this purpose, recent work has been focused on the first galectins known from outside the animal kingdom. These are the two isolectins from the basidiomycete Coprinus cinereus (inky cap mushroom), termed Cgl-1 and Cgl-2. Additionally, the close similarity (83% deduced amino-acid identity) but the pronounced difference in the expression patterns of these two fungal lectins during fruiting-body formation affords a suitable object for study of the relation of structural difference to the observed functional disparity in the same organism. Both galectins were crystallized after recombinant production. Crystals belong to either the orthorhombic space group C222(1) (Cgl-1) or the monoclinic space group P2(1) (Cgl-2). The latter crystals diffracted to 1.6 A resolution using synchrotron radiation. To solve the phasing problem, a selenomethionine-containing variant of Cgl-1 was designed. Crystals isomorphous to those of the native counterpart were obtained. Their structural analysis will also be crucial to solving the structure of Cgl-2.