title: Structural and functional insights into a peptide bond-forming bidomain from a nonribosomal peptide synthetase.
abstract: The crystal structure of the bidomain PCP-C from modules 5 and 6 of the nonribosomal tyrocidine synthetase TycC was determined at 1.8 A resolution. The bidomain structure reveals a V-shaped condensation domain, the canyon-like active site groove of which is associated with the preceding peptidyl carrier protein (PCP) domain at its donor side. The relative arrangement of the PCP and the peptide bond-forming condensation (C) domain places the active sites approximately 50 A apart. Accordingly, this PCP-C structure represents a conformational state prior to peptide transfer from the donor-PCP to the acceptor-PCP domain, implying the existence of additional states of PCP-C domain interaction during catalysis. Additionally, PCP-C exerts a mode of cyclization activity that mimics peptide bond formation catalyzed by C domains. Based on mutational data and pK value analysis of active site residues, it is suggested that nonribosomal peptide bond formation depends on electrostatic interactions rather than on general acid/base catalysis.
authors.affiliation: Department of Chemistry/Biochemistry, Philipps-Universität, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Samel
authors.forename: Georg
authors.initials: G
authors.lastname: Schoenafinger
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Knappe
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Marahiel
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Essen
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010453:Peptide Synthases / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D010455:Peptides; D010453:Peptide Synthases; C035180:tyrocidine synthetase