title: Cloning and characterization of the inulinase gene from a marine yeast Pichia guilliermondii and its expression in Pichia pastoris.
abstract: The extracellular inulinase structural gene was isolated from the genomic DNA of the marine yeast Pichia guilliermondii strain 1 by PCR. The gene had an open reading frame of 1,542 bp long encoding an inulinase. The coding region of the gene was not interrupted by any intron. It encoded 514 amino acid residues of a protein with a putative signal peptide of 18 amino acids and the calculated molecular mass of 58.04 kDa. The protein sequence deduced from the inulinase structural gene contained the inulinase consensus sequences (WMNXPNGL) and (RDPKVF). It also had ten conserved putative N-glycosylation sites. The inulinase from P. guilliermondii strain 1 was found to be closely related to that from Kluyveromyces marxianus. The inulinase gene without the signal sequence was subcloned into pPICZalphaA expression vector and expressed in Pichia pastoris X-33. The expressed fusion protein was analyzed by SDS-PAGE and western blotting and a specific band with molecular mass of about 60 kDa was found. Enzyme activity assay verified the recombinant protein as an inulinase. A maximum activity of 58.7 +/- 0.12 U/ml was obtained from the culture supernatant of P. pastoris X-33 harboring the inulinase gene. A large amount of monosaccharides, disaccharides and oligosaccharides were detected after the hydrolysis of inulin with the crude recombinant inulinase.
authors.affiliation: Unesco Chinese Center of Marine Biotechnology, Ocean University of China, Yushan Road, No. 5, Qingdao, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Gong
authors.forename: Zhe
authors.initials: Z
authors.lastname: Chi
authors.forename: Guanglei
authors.initials: G
authors.lastname: Liu
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Chi
authors.forename: Jun
authors.initials: J
authors.lastname: Sheng
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Xianghong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D056890:Eukaryota / Q000382:microbiology; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D007328:Insulin / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D010843:Pichia / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D007328:Insulin; D006026:Glycoside Hydrolases; C023086:inulinase