title: Purification, biochemical characterization, and genetic cloning of the phytase produced by Burkholderia sp. strain a13.
abstract: A phytase-producing bacterium, Burkholderia sp. a13 (JCM 30421), was isolated from Lake Kasumigaura by enrichment cultivation using minimum medium containing phytic acid as the sole phosphorus source. The phytase production by strain a13 was induced by the presence of phytic acid and repressed by the addition of glucose. The purified enzyme had a molecular weight of 44 kDa and a phytase activity of 174 μmol min(-1) mg(-1). The enzyme showed broad substrate specificity, but the highest activity was observed with phytic acid. The enzyme activity was strongly inhibited by Cu(2+), Zn(2+), Hg(2+), and iodoacetic acid, indicating the requirement of a thiol group for the activity. Genetic cloning reveals that the mature portion of this enzyme consists of 428 amino acids with a calculated molecular weight of 46 kDa. The amino acid sequence showed the highest similarity to the phytase produced by Hafnia alvei with 48% identity; it also contained histidine acid phosphatase (HAP) motifs (RHGXRXP and HD), indicating the classification of this enzyme in the HAP phytase family. We have successfully expressed the cloned gene in Escherichia coli from its putative initiation codon, showing that the gene actually encodes the phytase.
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba.
authors.forename: Eduardo Rezende
authors.initials: ER
authors.lastname: Graminho
authors.forename: Naoki
authors.initials: N
authors.lastname: Takaya
authors.forename: Akira
authors.initials: A
authors.lastname: Nakamura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hoshino
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D019117:Burkholderia / Q000201:enzymology* / Q000302:isolation & purification; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D020611:Hafnia alvei / Q000201:enzymology; D060106:Lakes / Q000382:microbiology*; D008969:Molecular Sequence Data; D010758:Phosphorus / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; D010758:Phosphorus; D010833:Phytic Acid; D010832:6-Phytase