title: Molecular and biochemical characterization of a new alkaline β-propeller phytase from the insect symbiotic bacterium Janthinobacterium sp. TN115.
abstract: A phytase-encoding gene (phyA115) was cloned from Janthinobacterium sp. TN115, a symbiotic bacterial strain isolated from the gut contents of Batocera horsfieldi larvae (Coleoptera: Cerambycidae), and expressed in Escherichia coli. The 1,884-bp full-length gene encodes a 28-residue putative signal peptide and a 599-residue mature protein with a calculated mass of 64 kDa. The deduced PhyA115 shares low identity with known sequences (47% at most) and contains an N-terminal incomplete domain (residues 29-297; domain N) and a typical β-propeller phytase domain at the C terminus (residues 298-627; domain C). Distinct from other β-propeller phytases that have neutral pH optima (pH 6.0-7.5), purified recombinant PhyA115 exhibits maximal activity at pH 8.5 and 45°C in the presence of 1 mM Ca(2+) and is highly active over a wider pH range (pH 6.0-9.0). These results indicate that PhyA115 is a β-propeller phytase that has application potential in aquaculture feed. To our knowledge, this is the first report of cloning of a phytase gene from the symbiotic microbes of an insect digestive tract and from the genus Janthinobacterium. The N-terminal incomplete domain is found to have no phytase activity but can influence the pH property of PhyA115.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing 100081, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Huoqing
authors.initials: H
authors.lastname: Huang
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Yuan
authors.forename: Pengjun
authors.initials: P
authors.lastname: Shi
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D010832:6-Phytase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D001517:Coleoptera / Q000382:microbiology* / Q000502:physiology; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D042802:Oxalobacteraceae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D010832:6-Phytase