scholarly journals Inversion of Extender Unit Selectivity in the Erythromycin Polyketide Synthase by Acyltransferase Domain Engineering

2016 ◽  
Vol 12 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Irina Koryakina ◽  
Christian Kasey ◽  
John B. McArthur ◽  
Andrew N. Lowell ◽  
Joseph A. Chemler ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Domain Engineering ◽  
Extender Unit

Divergolide congeners illuminate alternative reaction channels for ansamycin diversification

2015 ◽  
Vol 13 (6) ◽  
pp. 1618-1623 ◽  
Author(s):  
Ling Ding ◽  
Jakob Franke ◽  
Christian Hertweck
Keyword(s):  
Structure Elucidation ◽  
Polyketide Synthase ◽  
Ring Closure ◽  
Side Chain ◽  
Neighboring Group ◽  
Ring Contraction ◽  
Reaction Channels ◽  
Extender Unit

Isolation and structure elucidation of six new divergolides reveal unusual ansamycin diversification reactions including formation of the unusual isobutenyl side chain from a branched polyketide synthase extender unit, azepinone ring closure, macrolide ring contraction and formation of a seco variant by a neighboring group-assisted decarboxylation.

scholarly journals Computationally-guided exchange of substrate selectivity motifs in a modular polyketide synthase acyltransferase

2020 ◽  
Author(s):  
Edward Kalkreuter ◽  
Kyle S Bingham ◽  
Aaron M Keeler ◽  
Andrew N Lowell ◽  
Jennifer J. Schmidt ◽  
...  
Keyword(s):  
Active Site ◽  
Polyketide Synthase ◽  
Substrate Selectivity ◽  
Substrate Selection ◽  
Erythromycin Biosynthesis ◽  
Malonyl Coa ◽  
Extender Unit ◽  
Modular Polyketide Synthase ◽  
Dynamics Simulations

ABSTRACTAcyltransferases (ATs) of modular polyketide synthases catalyze the installation of malonyl-CoA extenders into polyketide scaffolds. Subsequently, AT domains have been targeted extensively to site-selectively introduce various extenders into polyketides. Yet, a complete inventory of AT residues responsible for substrate selection has not been established, critically limiting the efficiency and scope of AT engineering. Here, molecular dynamics simulations were used to prioritize ~50 mutations in the active site of EryAT6 from erythromycin biosynthesis. Following detailed in vitro studies, 13 mutations across 10 residues were identified to significantly impact extender unit selectivity, including nine residues that were previously unassociated with AT specificity. Unique insights gained from the MD studies and the novel EryAT6 mutations led to identification of two previously unexplored structural motifs within the AT active site. Remarkably, exchanging both motifs in EryAT6 with those from ATs with unusual extender specificities provided chimeric PKS modules with expanded and inverted substrate specificity. Our enhanced understanding of AT substrate selectivity and application of this motif-swapping strategy is expected to advance our ability to engineer PKSs towards designer polyketides.

scholarly journals Elucidating the mechanism of fluorinated extender unit loading for improved production of fluorine-containing polyketides

2017 ◽  
Vol 114 (5) ◽  
pp. E660-E668 ◽  
Author(s):  
Omer Ad ◽  
Benjamin W. Thuronyi ◽  
Michelle C. Y. Chang
Keyword(s):  
Polyketide Synthase ◽  
Acyl Carrier Protein ◽  
Type System ◽  
Large Family ◽  
Product Yield ◽  
Building Blocks ◽  
Chain Extension ◽  
Chain Elongation ◽  
Single Chain ◽  
Extender Unit

Polyketides are a large family of bioactive natural products synthesized by polyketide synthase (PKS) enzyme complexes predominantly from acetate and propionate. Given the structural diversity of compounds produced using these two simple building blocks, there has been longstanding interest in engineering the incorporation of alternative extender units. We have been investigating the mechanism of fluorinated monomer insertion by three of the six different modules of the PKS involved in erythromycin biosynthesis (6-deoxyerythronolide B synthase, DEBS) to begin understanding the contribution of different steps, such as enzyme acylation, transacylation, C–C bond formation, and chain transfer, to the overall selectivity and efficiency of this process. In these studies, we observe that inactivation of acis-acyltransferase (AT) domain to circumvent its native extender unit preference leads concurrently to a change of mechanism in which chain extension with fluorine-substituted extender units switches largely to an acyl carrier protein (ACP)-independent mode. This result suggests that the covalent linkage between the growing polyketide chain and the enzyme is lost in these cases, which would limit efficient chain elongation after insertion of a fluorinated monomer. However, use of a standalonetrans-acting AT to complement modules with catalytically deficient AT domains leads to enzyme acylation with the fluoromalonyl-CoA extender unit. Formation of the canonical ACP-linked intermediate with fluoromalonyl-CoA allows insertion of fluorinated extender units at 43% of the yield of the wild-type system while also amplifying product yield in single chain-extension experiments and enabling multiple chain extensions to form multiply fluorinated products.

scholarly journals Type III Polyketide Synthase β-Ketoacyl-ACP Starter Unit and Ethylmalonyl-CoA Extender Unit Selectivity Discovered byStreptomyces coelicolorGenome Mining

2006 ◽  
Vol 128 (46) ◽  
pp. 14754-14755 ◽  
Author(s):  
Lijiang Song ◽  
Francisco Barona-Gomez ◽  
Christophe Corre ◽  
Longkuan Xiang ◽  
Daniel W. Udwary ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Type Iii Polyketide Synthase ◽  
Type Iii ◽  
Starter Unit ◽  
Extender Unit

An Unusual Extender Unit Is Incorporated into the Modular Polyketide Synthase of Scopranones Biosynthesis

Biochemistry ◽  
2019 ◽  
Vol 58 (50) ◽  
pp. 5066-5073 ◽  
Author(s):  
Ayumu Demachi ◽  
Ryuji Uchida ◽  
Shiho Arima ◽  
Tohru Nagamitsu ◽  
Junko Hashimoto ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Extender Unit ◽  
Modular Polyketide Synthase
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