title: A remote but significant sequence homology between glycoside hydrolase clan GH-H and family GH31.
abstract: Although both the alpha-amylase super-family, i.e. the glycoside hydrolase (GH) clan GH-H (the GH families 13, 70 and 77), and family GH31 share some characteristics, their different catalytic machinery prevents classification of GH31 in clan GH-H. A significant but remote evolutionary relatedness is, however, proposed for clan GH-H with GH31. A sequence alignment, based on the idea that residues equivalent in the primordial catalytic GH-H/GH31 (beta/alpha)(8)-barrel may not be found in the present-day GH-H and GH31 structures at strictly equivalent positions, shows remote sequence homologies covering beta3, beta4, beta7 and beta8 of the GH-H and GH31 (beta/alpha)(8)-barrels. Structure comparison of GH13 alpha-amylase and GH31 alpha-xylosidase guided alignment of GH-H and GH31 members for construction of evolutionary trees. The closest sequence relationship displayed by GH31 is to GH77 of clan GH-H.
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, SK-84551 Bratislava, Slovakia. Stefan.Janecek@savba.sk
authors.forename: Stefan
authors.initials: S
authors.lastname: Janecek
authors.forename: Birte
authors.initials: B
authors.lastname: Svensson
authors.forename: E Ann
authors.initials: EA
authors.lastname: MacGregor
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000145:classification*; D005656:Fungal Proteins / Q000737:chemistry* / Q000145:classification*; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000145:classification*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D006026:Glycoside Hydrolases