The chemical ecology and physiological functions of type I polyketide natural products: the emerging picture.

Covering: up to 2024.For many years, the value of complex polyketides lay in their medical properties, including their antibiotic and antifungal activities, with little consideration paid to their native functions. However, more recent evidence gathered from the study of inter-organismal interactions has revealed the influence of these metabolites upon the ecological adaptation and distribution of their hosts, as well as their modes of communication.

Modular Cloning Tools for spp. and Application to the De Novo Biosynthesis of Flavokermesic Acid.

The filamentous are among the most prolific producers of bioactive natural products and are thus attractive chassis for the heterologous expression of native and designed biosynthetic pathways. Although suitable hosts exist, including genetically engineered cluster-free mutants, the approach is currently limited by the relative paucity of synthetic biology tools facilitating the de novo assembly of multicomponent gene clusters. Here, we report a modular system (MoClo) for including a set of adapted vectors and genetic elements, which allow for the construction of complete genetic circuits.

Insights into docking in megasynthases from the investigation of the toblerol -AT polyketide synthase: many α-helical means to an end.

The fidelity of biosynthesis by modular polyketide synthases (PKSs) depends on specific moderate affinity interactions between successive polypeptide subunits mediated by docking domains (DDs). These sequence elements are notably portable, allowing their transplantation into alternative biosynthetic and metabolic contexts. Herein, we use integrative structural biology to characterize a pair of DDs from the toblerol -AT PKS.

Biosynthesis of novel desferrioxamine derivatives requires unprecedented crosstalk between separate NRPS-independent siderophore pathways.

Iron is essential to many biological processes but its poor solubility in aerobic environments restricts its bioavailability. To overcome this limitation, bacteria have evolved a variety of strategies, including the production and secretion of iron-chelating siderophores. Here, we describe the discovery of four series of siderophores from ATCC23877, three of which are unprecedented.

Modular Oxime Formation by a trans-AT Polyketide Synthase.

Modular trans-acyltransferase polyketide synthases (trans-AT PKSs) are enzymatic assembly lines that biosynthesize complex polyketide natural products. Relative to their better studied cis-AT counterparts, the trans-AT PKSs introduce remarkable chemical diversity into their polyketide products. A notable example is the lobatamide A PKS, which incorporates a methylated oxime.

Decrypting the programming of β-methylation in virginiamycin M biosynthesis.

During biosynthesis by multi-modular trans-AT polyketide synthases, polyketide structural space can be expanded by conversion of initially-formed electrophilic β-ketones into β-alkyl groups. These multi-step transformations are catalysed by 3-hydroxy-3-methylgluratryl synthase cassettes of enzymes. While mechanistic aspects of these reactions have been delineated, little information is available concerning how the cassettes select the specific polyketide intermediate(s) to target.

Engineering Modular Polyketide Biosynthesis in Streptomyces Using CRISPR/Cas: A Practical Guide.

The CRISPR/Cas system, which has been widely applied to organisms ranging from microbes to animals, is currently being adapted for use in Streptomyces bacteria. In this case, it is notably applied to rationally modify the biosynthetic pathways giving rise to the polyketide natural products, which are heavily exploited in the medical and agricultural arenas. Our aim here is to provide the potential user with a practical guide to exploit this approach for manipulating polyketide biosynthesis, by treating key experimental aspects including vector choice, design of the basic engineering components, and trouble-shooting.

Engineering the stambomycin modular polyketide synthase yields 37-membered mini-stambomycins.

The modular organization of the type I polyketide synthases (PKSs) would seem propitious for rational engineering of desirable analogous. However, despite decades of efforts, such experiments remain largely inefficient. Here, we combine multiple, state-of-the-art approaches to reprogram the stambomycin PKS by deleting seven internal modules.

Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Manipulating polyketide stereochemistry by exchange of polyketide synthase modules.

A key goal of modular polyketide synthase (PKS) engineering is to alter polyketide stereochemistry. Here we report that exchanging whole PKS modules is a more productive approach than swapping individual ketoreductase (KR) domains for introducing rare 'A2' and 'B2' stereochemistry into model polyketides, and identify four modular 'biobricks' for such synthetic biology efforts.

Towards improved understanding of intersubunit interactions in modular polyketide biosynthesis: Docking in the enacyloxin IIa polyketide synthase.

Modular polyketide synthases (PKSs) are molecular-scale assembly lines comprising multiple gigantic polypeptide subunits. Faithful ordering of the subunits is mediated by extreme C- and N-terminal regions called docking domains (DDs). Decrypting how specificity is achieved by these elements is important both for understanding PKS function and modifying it to generate useful polyketide analogues for biological evaluation.

Author Correction: Insights into a dual function amide oxidase/macrocyclase from lankacidin biosynthesis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: Insights into a dual function amide oxidase/macrocyclase from lankacidin biosynthesis.

In the original version of this Article, the final concentration of riboflavin in the supplemented LB medium for recombinant LkcE expression was incorrectly stated as 1 g L (this was the concentration of the stock solution) and should have read 10-50 mg L-. This error has been corrected in both the PDF and HTML versions of the Article.

Insights into a dual function amide oxidase/macrocyclase from lankacidin biosynthesis.

Acquisition of new catalytic activity is a relatively rare evolutionary event. A striking example appears in the pathway to the antibiotic lankacidin, as a monoamine oxidase (MAO) family member, LkcE, catalyzes both an unusual amide oxidation, and a subsequent intramolecular Mannich reaction to form the polyketide macrocycle. We report evidence here for the molecular basis for this dual activity.

Unpackaging the Roles of Streptomyces Natural Products.

Streptomyces are the principle source of antibiotics in clinical use, but what the bacteria use these molecules for remains largely a mystery. In this issue of Cell Chemical Biology, Hoefler et al. (2017) demonstrate a direct link between biosynthesis of the polyketide linearmycins and extracellular membrane vesicles.

Correction: Uncovering the structures of modular polyketide synthases.

Correction for 'Uncovering the structures of modular polyketide synthases' by Kira J. Weissman, Nat. Prod.

Polyketide stereocontrol: a study in chemical biology.

The biosynthesis of reduced polyketides in bacteria by modular polyketide synthases (PKSs) proceeds with exquisite stereocontrol. As the stereochemistry is intimately linked to the strong bioactivity of these molecules, the origins of stereochemical control are of significant interest in attempts to create derivatives of these compounds by genetic engineering. In this review, we discuss the current state of knowledge regarding this key aspect of the biosynthetic pathways.

Characterization of Intersubunit Communication in the Virginiamycin trans-Acyl Transferase Polyketide Synthase.

Modular polyketide synthases (PKSs) direct the biosynthesis of clinically valuable secondary metabolites in bacteria. The fidelity of chain growth depends on specific recognition between successive subunits in each assembly line: interactions mediated by C- and N-terminal "docking domains" (DDs). We have identified a new family of DDs in trans-acyl transferase PKSs, exemplified by a matched pair from the virginiamycin (Vir) system.

Genetic engineering of modular PKSs: from combinatorial biosynthesis to synthetic biology.

Multienzyme polyketide synthases (PKSs) are molecular-scale assembly lines which construct complex natural products in bacteria. The underlying modular architecture of these gigantic catalysts inspired, from the moment of their discovery, attempts to modify them by genetic engineering to produce analogues of predictable structure. These efforts have resulted in hundreds of metabolites new to nature, as detailed in this review.

The structural biology of biosynthetic megaenzymes.

The modular polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) are among the largest and most complicated enzymes in nature. In these biosynthetic systems, independently folding protein domains, which are organized into units called 'modules', operate in assembly-line fashion to construct polymeric chains and tailor their functionalities. Products of PKSs and NRPSs include a number of blockbuster medicines, and this has motivated researchers to understand how they operate so that they can be modified by genetic engineering.