Forschung & Innovation
Publikationen
Atypical Condensation Domains Guide Discovery and Illuminate Biosynthesis of Myxoglucamides Featuring Vinyl-Substituted, α-Oxidized γ-Amino Acids
PMU Autor*in
Alexander Popoff
Alle Autor*innen
Tingting Wang, Alexander Popoff, Maja Hunter, Guangzhi Dai, Ronald Garcia, Huixin Xu, Haowen Zhao, Asfandyar Sikandar, Liujie Huo, Rolf Muller, Chengzhang Fu
Fachzeitschrift
ANGEWANDTE CHEMIE
Kurzfassung
Condensation (C) domains in nonribosomal peptide synthetase (NRPS) pathways exhibit versatile functions that drive biosynthetic and chemical novelty. Through genome mining for atypical C domains, we identified a hybrid NRPS/polyketide synthase (PKS) biosynthetic gene cluster (mxg) from Cystobacterineae sp. MCy9003 and discovered myxoglucamides, a family of glycolipopeptides featuring an unprecedented vinyl-substituted gamma-amino acid bearing an alpha-hydroxy/alpha-ketoamide functionality. Heterologous expression of the promoter-refactored pathway revealed new O-acylated myxoglucamides, and subsequent studies unveiled the C domain-like enzyme MxgH as a promiscuous O-acyltransferase decorating the glucose moiety with short-chain acyl groups. Biosynthetic investigations demonstrated that the unusual gamma-amino acid originates from l-glutamate. Completion of the cryptic beta-hydroxylation of peptidyl carrier protein-tethered glutamate by the alpha-ketoglutarate-dependent dioxygenase OxMxgA occurs only concomitantly with upstream chain extension, revealing a bidirectional checkpoint for substrate fidelity. Unexpectedly, the C-domain-like interface domain IMxgB is dispensable for this coupled transformation. Mutational analysis of the FMN-dependent monooxygenase encoded by mxgE, together with characterization of a shunt metabolite, supported its role in alpha-oxidation for alpha-hydroxy/alpha-ketoamide formation during gamma-amino acid assembly. Together, these findings uncover an unrecognized biosynthetic logic for generating vinyl-substituted, alpha-oxidized gamma-amino acids and substantially expand the functional repertoire of NRPS/PKS assembly lines.
Keywords
O-acylation, Beta-hydroxylation, Condensation domains, Gamma-amino acids, Glycolipopeptides