title: Production of a fully functional, permuted single-chain penicillin G acylase.
abstract: Penicillin G acylase (PGA) is a heterodimeric enzyme synthesized as a single-polypeptide precursor that undergoes an autocatalytic processing to remove an internal spacer peptide to produce the active enzyme. We constructed a single-chain PGA not dependent on autoproteolytic processing. The mature sequence of the beta-domain was expressed as the N terminus of a new polypeptide, connected by a random tetra-peptide to the alpha-domain, to afford a permuted protein. We found several active enzymes among variants differing in their linker peptides. Protein expression analysis showed that the functional single-chain variants were produced when using a Sec-dependent leader peptide, or when expressed inside the bacterial cytoplasm. Active-site titration experiments showed that the single-chain proteins displayed similar k(cat) values to the ones obtained with the wild-type enzyme. Interestingly, the single-chain proteins also displayed close to 100% of functional active sites compared to 40% to 70% functional yield usually obtained with the heterodimeric protein.
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología/Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, México.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Flores
authors.forename: Xavier
authors.initials: X
authors.lastname: Soberón
authors.forename: Joel
authors.initials: J
authors.lastname: Osuna
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010399:Penicillin Amidase / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D010399:Penicillin Amidase