title: Cloning of genes of the aminopeptidase T family from Thermus thermophilus HB8 and Bacillus stearothermophilus NCIB8924: apparent similarity to the leucyl aminopeptidase family.
abstract: To obtain genes with sequence similarity to aminopeptidase T (AP-T) of Thermus aquaticus YT-1, we cloned the genes encoding aminopeptidase Th (AP-Th) from Thermus thermophilus HB8 and aminopeptidase II (APII) from Bacillus stearothermophilus NCIB8924. The AP-Th gene encoded a polypeptide of 408 amino acid residues and the deduced molecular weight of this subunit was 45,015. The APII gene encoded a polypeptide of 413 amino acid residues with a deduced molecular weight of 46,207. The extent of amino acid sequence similarity between AP-Th and AP-T was 86%, and that between APII and AP-T was 43%. The substrate specificities of these expressed enzymes were similar, and each efficiently hydrolyzed leucyl- or phenyl-peptide substrates. Since the deduced amino acid sequence of these enzymes show no similarity to other known aminopeptidases, they appear to comprise an independent family of peptidases, designated the AP-T family. However, a conserved region within the enzymes of the AP-T family shows similarity to the active site signature of the leucyl aminopeptidase family, suggesting that these enzymes may belong to the leucyl aminopeptidase superfamily.
authors.affiliation: Research Center, Yotsuba Milk Products Co., Ltd., Hokkaido, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Motoshima
authors.forename: E
authors.initials: E
authors.lastname: Minagawa
authors.forename: F
authors.initials: F
authors.lastname: Tsukasaki
authors.forename: S
authors.initials: S
authors.lastname: Kaminogawa
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000235:genetics*; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics; D005470:Fluorometry; D015971:Gene Expression Regulation, Enzymologic; D001411:Geobacillus stearothermophilus / Q000201:enzymology* / Q000235:genetics; D007931:Leucyl Aminopeptidase / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010957:Plasmids; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D000626:Aminopeptidases; C067298:aminopeptidase T protein, Thermus aquaticus; D007931:Leucyl Aminopeptidase