title: Inhibitor-assisted refolding of protease: a protease inhibitor as an intramolecular chaperone.
abstract: Pleurotus ostrearus proteinase A inhibitor 1 (POIA1), which was discovered as a protease inhibitor, is unique in that it shows sequence homology to the propeptide of subtilisin, which functions as an intramolecular of a cognate protease. In this study, we demonstrate that POIA1 can function as an intramolecular chaperone of subtilisin by in vitro and in vivo experiments. The specific cleavage between POIA1 and the mature region of subtilisin BPN' occurred in a refolding process of a chimera protein, and Bacillus cells transformed with a chimera gene formed a halo on a skim milk plate. The mutational analyses of POIA1 in the chimera protein suggested that the tertiary structure of POIA1 is required for such a function, and that an increase in its ability to bind to subtilisin BPN' makes POIA1 a more effective intramolecular chaperone.
authors.affiliation: Institute for Biomolecular Science, Gakushuin University, Mejiro, Tokyo 171-8588, Japan. shuichi.kojima@gakushuin.ac.jp
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kojima
authors.forename: Akane
authors.initials: A
authors.lastname: Iwahara
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yanai
mesh_terms: D000409:Alanine / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001412:Bacillus subtilis / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010649:Phenylalanine / Q000235:genetics; D020076:Pleurotus / Q000201:enzymology*; D011480:Protease Inhibitors / Q000378:metabolism*; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013381:Subtilisins / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D018832:Molecular Chaperones; D011480:Protease Inhibitors; D011993:Recombinant Fusion Proteins; D010649:Phenylalanine; D013381:Subtilisins; D000409:Alanine