HMM Summary Page: TIGR01515

Function1,4-alpha-glucan branching enzyme
Gene SymbolglgB
Trusted Cutoff463.95
Domain Trusted Cutoff463.95
Noise Cutoff262.00
Domain Noise Cutoff262.00
Isology Typeequivalog
EC Number2.4.1.18
HMM Length607
Mainrole CategoryEnergy metabolism
Subrole CategoryBiosynthesis and degradation of polysaccharides
Gene Ontology TermGO:0003844: 1,4-alpha-glucan branching enzyme activity molecular_function
GO:0005978: glycogen biosynthetic process biological_process
AuthorSelengut J
Entry DateMay 20 2002 3:13PM
Last ModifiedFeb 14 2011 3:27PM
CommentThis HMM describes the glycogen branching enzymes which are responsible for the transfer of chains of approx. 7 alpha(1--4)-linked glucosyl residues to other similar chains (in new alpha(1--6) linkages) in the biosynthesis of glycogen. This enzyme is a member of the broader amylase family of starch hydrolases which fold as (beta/alpha)8 barrels, the so-called TIM-barrel structure [1,2]. All of the sequences comprising the seed of this model have been experimentally characterized. (For instance, [3]). This model encompasses both bacterial and eukaryotic species. No archaea have this enzyme, although Aquifex aolicus does. Two species, Bacillus thuringiensis and Clostridium perfringens have two sequences each which are annotated as amylases. These annotations are aparrently in error. GP|18143720 from C. perfringens, for instance, contains the note "674 aa, similar to gp:A14658_1 amylase (1,4-alpha-glucan branching enzyme (EC ) from Bacillus thuringiensis (648 aa); 51.1% identity in 632 aa overlap." A branching enzyme from Porphyromonas gingivales, OMNI|PG1793, appears to be more closely related to the eukaryotic species (across a deep phylogenetic split) and may represent an instance of lateral transfer from this species' host. A sequence from Arabidopsis thaliana, GP|9294564, scores just above trusted, but appears either to contain corrupt sequence or, more likely, to be a pseudogene as some of the conserved catalytic residues common to the alpha amylase family are not conserved here.
ReferencesRN [1] RM PMID: 11257505 RT Relationship of sequence and structure to specificity in the alpha-amylase family of enzymes. RA MacGregor EA, Janecek S, Svensson B. RL Biochim Biophys Acta 2001 Mar 9;1546(1):1-20 RN [2] RM PMID: 9758744 RT High-level expression of branching enzyme II from maize endosperm in Escherichia coli. RA Libessart N, Preiss J. RL Protein Expr Purif 1998 Oct;14(1):1-7 RN [3] RM PMID: 407932 RT Biosynthesis of bacterial glycogen. Purification and properties of the Escherichia coli b alpha-1,4,-glucan: alpha-1,4-glucan 6-glycosyltansferase. RA Boyer C, Preiss J. RL Biochemistry. 1977 Aug 9;16(16):3693-9. DR HAMAP; MF_00685; 240 of 243
Genome PropertyGenProp0168: glycogen system (HMM)