title: Effect of salt on the activity of Streptomyces prolyl aminopeptidase.
abstract: A salt-tolerant prolyl aminopeptidase from Streptomyces aureofaciens TH-3 (TH-3PAP) was purified from a culture supernatant. The gene encoding TH-3PAP was cloned and sequenced. The primary structure of TH-3PAP showed 65% identity with that of PAP from Streptomyces lividans (SLPAP) and possessed a conserved catalytic motif, GxSxGG, which is conserved in the alpha/beta hydrolase fold family. The characterization of the recombinants TH-3PAP and SLPAP indicated a difference: in 4.0 M NaCl, TH-3PAP showed enzyme activity, whereas SLPAP was inactive. Next, we constructed chimeras between TH-3PAP and SLPAP using an in vivo DNA shuffling system and a sandwich chimera (sc-PAP), whose region from 63 to 78 amino acids of TH-3PAP was substituted with that of SLPAP. Comparison of the biochemical properties between TH-3PAP and the salt-sensitive sc-PAP suggested that the fine tuning of the N-terminal conformation of TH-3PAP by hydrophobic interaction is important for the salt tolerance mechanism of the enzyme.
authors.affiliation: Research Institute for Biological Sciences (RIBS), Okayama, Kaga-gun, Okayama 716-1241, Japan.
authors.forename: Misugi
authors.initials: M
authors.lastname: Uraji
authors.forename: Jiro
authors.initials: J
authors.lastname: Arima
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Uesugi
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwabuchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hatanaka
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012965:Sodium Chloride / Q000494:pharmacology; D013304:Streptomyces aureofaciens / Q000201:enzymology* / Q000235:genetics; D048170:Streptomyces lividans / Q000201:enzymology* / Q000235:genetics
chemical_list: D012965:Sodium Chloride; D000626:Aminopeptidases; C022450:prolyl aminopeptidase