Loss of Single‐Domain Function in a Modular Assembly Line Alters the Size and Shape of a Complex Polyketide

• Published in: Angewandte Chemie Vol. 131; no. 50; pp. 18420 - 18424
• Main Authors: Peng, Huiyun, Ishida, Keishi, Hertweck, Christian
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09.12.2019
• Subjects: Assembly lines; Biological evolution; Biosynthese; Biotransformation; Chemistry; Fungicides; Metabolites; Modules; Modulsprung; Mutagenesis; Mutation; Naturstoffe; Point mutation; Polyketide synthase; Polyketidsynthasen; Synthetische Biologie
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201911315

The structural wealth of complex polyketide metabolites produced by bacteria results from intricate, highly evolved biosynthetic programs of modular assembly lines, in which the number of modules defines the size of the backbone, and the domain composition controls the degree of functionalization. We report a remarkable case where polyketide chain length and scaffold depend on the function of a single β‐keto processing domain: A ketoreductase domain represents a switch between diverging biosynthetic pathways leading either to the antifungal aureothin or to the nematicidal luteoreticulin. By a combination of heterologous expression, mutagenesis, metabolite analyses, and in vitro biotransformation we elucidate the factors governing non‐colinear polyketide assembly involving module skipping and demonstrate that a simple point mutation in type I polyketide synthase (PKS) can have a dramatic effect on the metabolic profile. This finding sheds new light on possible evolutionary scenarios and may inspire future synthetic biology approaches. Biosynthetischer Schalter: Genetische und chemische Analysen zeigten einen bemerkenswerten Fall, in dem die Länge der Polyketidkette und das Gerüst von der Funktion einer einzelnen β‐Keto‐Prozessierungsdomäne einer multimodularen Polyketidsynthase abhängen. Eine Ketoreduktasedomäne wirkt als molekularer Schalter zwischen divergierenden Routen, die entweder zum antimykotischen Aureothin oder zum nematiziden Luteoreticulin führen.