title: Substrate specificity at the P1' site of Escherichia coli OmpT under denaturing conditions.
abstract: Though OmpT has been reported to mainly cleave the peptide bond between consecutive basic amino acids, we identified more precise substrate specificity by using a series of modified substrates, termed PRX fusion proteins, consisting of 184 residues. The cleavage site of the substrate PRR was Arg140-Arg141 and the modified substrates PRX substituted all 19 natural amino acids at the P1' site instead of Arg141. OmpT under denaturing conditions (in the presence of 4 M urea) cleaved not only between two consecutive basic amino acids but also at the carboxyl side of Arg140 except for the Arg140-Asp141, -Glu141, and -Pro141 pairs. In addition to Arg140 at the P1 site, similar results were obtained when Lys140 was substituted into the P1 site. In the absence of urea, an aspartic acid residue at the P1' site was unfavorable for OmpT cleavage of synthetic decapeptides, the enzyme showed a preference for a dibasic site.
authors.affiliation: Suntory Institute for Medicinal Research and Development, Ohra-gun, Gunma, Japan. Kazuaki_Okuno@suntory.co.jp
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Okuno
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yabuta
authors.forename: Kouji
authors.initials: K
authors.lastname: Kawanishi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ohsuye
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ooi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D001665:Binding Sites; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008239:Lysine; D010455:Peptides; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D010455:Peptides; D012697:Serine Endopeptidases; C057840:omptin outer membrane protease; D008239:Lysine