Genomics-driven discovery of the biosynthetic gene cluster of maduramicin and its overproduction in Actinomadura sp. J1-007

Abstract

Maduramicin is the most efficient and possesses the largest market share of all anti-coccidiosis polyether antibiotics (ionophore); however, its biosynthetic gene cluster (BGC) has yet to been identified, and the associated strains have not been genetically engineered. Herein, we performed whole-genome sequencing of a maduramicin-producing industrial strain of Actinomadura sp. J1-007 and identified its BGC. Additionally, we analyzed the identified BGCs in silico to predict the biosynthetic pathway of maduramicin. We then developed a conjugation method for the non-spore-forming Actinomadura sp. J1-007, consisting of a site-specific integration method for gene overexpression. The maduramicin titer increased by 30% to 7.16 g/L in shake-flask fermentation following overexpression of type II thioesterase MadTE that is the highest titer at present. Our findings provide insights into the biosynthetic mechanism of polyethers and provide a platform for the metabolic engineering of maduramicin-producing microorganisms for overproduction and development of maduramicin analogs in the future.

Chain release mechanisms in polyketide and non-ribosomal peptide biosynthesis

“…11A). Such examples are found in the biosynthetic pathways of the bacterial polyether ionophores nigericin (27), 95 monensin (PK) (28), 96 nanchangmycin (PK) (29), 97,98 and maduramicin (PK) 99 (Fig. 11B).…”

“…In these cases, aer the nal extension reaction has occurred the PK chain is transferred to a standalone ACP protein, followed by hydrolytic release catalysed by a TEII enzyme. 95,96,98,99 TEII enzymes also catalyse the hydrolytic chain release of non-polyethers, including zaragozic acid, 100 colibactin, 101 kinamycin (30), 102 and possibly indanomycin. 22,103 Kinamycin is noteworthy as it is a type II polyketide.…”

Enzyme-Catalyzed Spiroacetal Formation in Polyketide Antibiotic Biosynthesis

“…One such NigO-like enzyme, MadU, is located in a known gene cluster in Actinomadura sp. J1-007 for the production of the [6,5]-spiroacetal-containing polyether antibiotic maduramicin . Several putative spirocyclases were identified related to Aln8, a protein of unknown function from the alnumycin biosynthetic pathway in Streptomyces sp.…”

Synthetic and biosynthetic methods for selective cyclisations of 4,5-epoxy alcohols to tetrahydropyrans

“…However, the epoxide opening activity was dramatically enhanced with the addition of MonBI to the MonBII reaction mixture. 129 Other epoxide hydrolases that have been proposed to be involved in THF ring biosynthesis include SalBI/SalBII and from salinomycin pathway, 130 NigBI/NigBII from the nigericin pathway, 131 NanI from the nanchangmycin, 132 MadI from the maduramicin pathway, 133 and Pak24/Pak25 from the K-41A pathway. 134…”