title: Structural model for family 32 of glycosyl-hydrolase enzymes.
abstract: A structural model is presented for family 32 of the glycosyl-hydrolase enzymes based on the beta-propeller fold. The model is derived from the common prediction of two different threading methods, TOPITS and THREADER. In addition, we used a correlated mutation analysis and prediction of active-site residues to corroborate the proposed model. Physical techniques (circular dichroism and differential scanning calorimetry) confirmed two aspects of the prediction, the proposed all-beta fold and the multi-domain structure. The most reliable three-dimensional model was obtained using the structure of neuraminidase (1nscA) as template. The analysis of the position of the active site residues in this model is compatible with the catalytic mechanism proposed by Reddy and Maley (J. Biol. Chem. 271:13953-13958, 1996), which includes three conserved residues, Asp, Glu, and Cys. Based on this analysis, we propose the participation of one more conserved residue (Asp 162) in the catalytic mechanism. The model will facilitate further studies of the physical and biochemical characteristics of family 32 of the glycosyl-hydrolases.
authors.affiliation: Centro de Ingeniería Genética y Biotecnología, Havana, Cuba. Tirso.Pons@CIGB.edu.cu
authors.forename: T
authors.initials: T
authors.lastname: Pons
authors.forename: O
authors.initials: O
authors.lastname: Olmea
authors.forename: G
authors.initials: G
authors.lastname: Chinea
authors.forename: A
authors.initials: A
authors.lastname: Beldarraín
authors.forename: G
authors.initials: G
authors.lastname: Márquez
authors.forename: N
authors.initials: N
authors.lastname: Acosta
authors.forename: L
authors.initials: L
authors.lastname: Rodríguez
authors.forename: A
authors.initials: A
authors.lastname: Valencia
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002942:Circular Dichroism; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006602:Hexosyltransferases / Q000737:chemistry*; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D043324:beta-Fructofuranosidase
chemical_list: D001426:Bacterial Proteins; D006602:Hexosyltransferases; C021513:levansucrase; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; C021512:levanase; C023086:inulinase