title: A novel thermostable branching enzyme from an extremely thermophilic bacterial species, Rhodothermus obamensis.
abstract: A branching enzyme (EC 2.4.1.18) gene was isolated from an extremely thermophilic bacterium, Rhodothermus obamensis. The predicted protein encodes a polypeptide of 621 amino acids with a predicted molecular mass of 72 kDa. The deduced amino acid sequence shares 42-50% similarity to known bacterial branching enzyme sequences. Similar to the Bacillus branching enzymes, the predicted protein has a shorter N-terminal amino acid extension than that of the Escherichia coli branching enzyme. The deduced amino acid sequence does not appear to contain a signal sequence, suggesting that it is an intracellular enzyme. The R. obamensis branching enzyme was successfully expressed both in E. coli and a filamentous fungus, Aspergillus oryzae. The enzyme showed optimum catalytic activity at pH 6.0-6.5 and 65 degrees C. The enzyme was stable after 30 min at 80 degrees C and retained 50% of activity at 80 degrees C after 16 h. Branching activity of the enzyme was higher toward amylose than toward amylopectin. This is the first thermostable branching enzyme isolated from an extreme thermophile.
authors.affiliation: Novozymes Japan Ltd, Makuhari Techno Garden, Chiba-shi, Japan.
authors.forename: M L
authors.initials: ML
authors.lastname: Shinohara
authors.forename: M
authors.initials: M
authors.lastname: Ihara
authors.forename: M
authors.initials: M
authors.lastname: Abo
authors.forename: M
authors.initials: M
authors.lastname: Hashida
authors.forename: S
authors.initials: S
authors.lastname: Takagi
authors.forename: T C
authors.initials: TC
authors.lastname: Beck
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001236:Aspergillus oryzae / Q000201:enzymology / Q000235:genetics; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D004269:DNA, Bacterial; D011994:Recombinant Proteins; D015061:1,4-alpha-Glucan Branching Enzyme