title: Synthesis of linear gramicidin requires the cooperation of two independent reductases.
abstract: The linear pentadecapeptide gramicidin has been reported to be assembled by four large multimodular nonribosomal peptide synthetases (NRPSs), LgrABCD, that comprise 16 modules. During biosynthesis, the N-formylated 16mer peptide is bound to the peptidyl carrier protein (PCP) of the terminal module via a thioester bond to the carboxyl group of the last amino acid glycine(16). In a first reaction the peptide is released from the protein template in an NAD(P)H-dependent reduction step catalyzed by the adjacent reductase forming an aldehyde intermediate. Here we present the biochemical proof that this aldehyde intermediate is further reduced by an aldoreductase, LgrE, in an NADPH-dependent manner to form the final product gramicidin A, N-formyl-pentadecapeptide-ethanolamine. To determine the potential use of the two reductases in the construction of hybrid NRPSs, we have tested their ability to accept a variety of different substrates in vitro. The results obtained give way to a broad spectrum of possible use.
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Schracke
authors.forename: Uwe
authors.initials: U
authors.lastname: Linne
authors.forename: Christoph
authors.initials: C
authors.lastname: Mahlert
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Marahiel
mesh_terms: D000449:Aldehyde Reductase / Q000737:chemistry* / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D006096:Gramicidin / Q000096:biosynthesis* / Q000737:chemistry; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D005810:Multigene Family; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010452:Peptide Biosynthesis; D010453:Peptide Synthases / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D009097:Multienzyme Complexes; D006096:Gramicidin; D010088:Oxidoreductases; D000449:Aldehyde Reductase; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase