Structural analysis of Saccharomyces cerevisiae alpha-galactosidase and its complexes with natural substrates reveals new insights into substrate specificity of GH27 glycosidases.

ABSTRACT: Alpha-galactosidases catalyze the hydrolysis of terminal alpha-1,6-galactosyl units from galacto-oligosaccharides and polymeric galactomannans. The crystal structures of tetrameric Saccharomyces cerevisiae alpha-galactosidase and its complexes with the substrates melibiose and raffinose have been determined to 1.95, 2.40, and 2.70 A resolution. The monomer folds into a catalytic (alpha/beta)(8) barrel and a C-terminal beta-sandwich domain with unassigned function. This pattern is conserved with other family 27 glycosidases, but this enzyme presents a unique 45-residue insertion in the beta-sandwich domain that folds over the barrel protecting it from the solvent and likely explaining its high stability. The structure of the complexes and the mutational analysis show that oligomerization is

SUBMITTER: Fernandez-Leiro R 

PROVIDER: S-EPMC2934667 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature