Natural Products In Microorganisms Research Articles

Engineered production of bioactive natural products from medicinal plants

Plant natural products have been particularly important due to their use in food, cosmetic, and pharmaceutical industries. In particular, Traditional Chinese Medicine provides a precious potential for the discovery of bioactive natural products and development of novel modern medicines. However, the existing production methods for plant natural products such as chemical synthesis and plant extraction does not meet the current demand. Due to their environmental and economic concerns, engineered production of valuable natural products in microbial hosts has become an attractive alternative platform. This review covers the recent advances in the engineered production of plant natural products in microorganisms. A special focus was placed on the biotechnological production of plant-derived terpenoids, flavonoids, and alkaloids. Some successful examples of engineered production of plant natural products (or their precursors) such as artemisinin, paclitaxel, naringenin, quercetin, berberine, and noscapine are summarized. This clearly indicates that the engineered production method is a promising approach with various advantages over current methods.

Engineered production of bioactive natural products from medicinal plants

Plant natural products have been particularly important due to their use in food, cosmetic, and pharmaceutical industries. In particular, Traditional Chinese Medicine provides a precious potential for the discovery of bioactive natural products and development of novel modern medicines. However, the existing production methods for plant natural products such as chemical synthesis and plant extraction does not meet the current demand. Due to their environmental and economic concerns, engineered production of valuable natural products in microbial hosts has become an attractive alternative platform. This review covers the recent advances in the engineered production of plant natural products in microorganisms. A special focus was placed on the biotechnological production of plant-derived terpenoids, flavonoids, and alkaloids. Some successful examples of engineered production of plant natural products (or their precursors) such as artemisinin, paclitaxel, naringenin, quercetin, berberine, and noscapine are summarized. This clearly indicates that the engineered production method is a promising approach with various advantages over current methods.

Functional Integration of Two CYP450 Genes Involved in Biosynthesis of Tanshinones for Improved Diterpenoid Production by Synthetic Biology.

Cytochrome P450s (CYPs) are important enzymes in the secondary metabolism of plants and have been recognized as key players in bioengineering and synthetic biology. Previously reported CYP76AH1 and CYP76AH3, having greater than 80% sequence homology, played a continuous catalytic role in the biosynthesis of tanshinones in Salvia miltiorrhiza. Homology modeling indicates that four sites might be responsible for differences in catalytic activity between the two enzymes. A series of modeling-based mutational variants of CYP76AH1 were designed to integrate the functions of the two CYPs. The mutant CYP76AH1D301E,V479F, which integrated the functions of CYP76AH1 and CYP76AH3, was found to efficiently catalyze C11 and C12 hydroxylation and C7 oxidation of miltiradiene substrates. Integration and utilization of CYP76AH1D301E,V479F by synthetic biology methods allowed the robust production of 11-hydroxy ferruginol, sugiol, and 11-hydroxy sugiol in yeast. The functionally integrated CYP gene after active site modifications improves catalytic efficiency by reducing the transfer of intermediate metabolites between component proteins. This provides a synthetic biology reference for improving the catalytic efficiencies of systems that produce plant natural products in microorganisms.

Protein Acylation is a General Regulatory Mechanism in Biosynthetic Pathway of Acyl-CoA-Derived Natural Products

Coenzyme A (CoA) esters of short fatty acids (acyl-CoAs) function as key precursors for the biosynthesis of various natural products and the dominant donors for lysine acylation. Herein, we investigated the functional interplay between beneficial and adverse effects of acyl-CoA supplements on the production of acyl-CoA-derived natural products in microorganisms by using erythromycin-biosynthesized Saccharopolyspora erythraea as a model: accumulation of propionyl-CoA benefited erythromycin biosynthesis, but lysine propionylation inhibited the activities of important enzymes involved in biosynthetic pathways of erythromycin. The results showed that the overexpression of NAD+-dependent deacylase could circumvent the inhibitory effects of high acyl-CoA concentrations. In addition, we demonstrated the similar lysine acylation mechanism in other acyl-CoA-derived natural product biosynthesis, such as malonyl-CoA-derived alkaloid and butyryl-CoA-derived bioalcohol. These observations systematically uncovered the important role of protein acylation on interaction between the accumulation of high concentrations of acyl-CoAs and the efficiency of their use in metabolic pathways.

Heterologous Production and Yield Improvement of Epothilones in Burkholderiales Strain DSM 7029.

The cloning of microbial natural product biosynthetic gene clusters and their heterologous expression in a suitable host have proven to be a feasible approach to improve the yield of valuable natural products and to begin mining cryptic natural products in microorganisms. Myxobacteria are a prolific source of novel bioactive natural products with only limited choices of heterologous hosts that have been exploited. Here, we describe the use of Burkholderiales strain DSM 7029 as a potential heterologous host for the functional expression of myxobacterial secondary metabolites. Using a newly established electroporation procedure, the 56 kb epothilone biosynthetic gene cluster from the myxobacterium Sorangium cellulosum was introduced into the chromosome of strain DSM 7029 by transposition. Production of epothilones A, B, C, and D was detected despite their yields being low. Optimization of the medium, introduction of the exogenous methylmalonyl-CoA biosynthetic pathway, and overexpression of rare tRNA genes resulted in an approximately 75-fold increase in the total yields of epothilones to 307 μg L-1. These results show that strain DSM 7029 has the potential to produce epothilones with reasonable titers and might be a broadly applicable host for the heterologous expression of other myxobacterial polyketide synthases and nonribosomal peptide synthetases, expediting the process of genome mining.

Engineered Biosynthesis of Medicinally Important Plant Natural Products in Microorganisms.

Plants produce structurally and functionally diverse natural products. Some of these compounds possess promising health-benefiting properties, such as resveratrol (antioxidant) curcumin (anti-inflammatory, anti-allergic and anticancer), paclitaxel (anticancer) and artemisinin (antimalarial). These compounds are produced through particular biosynthetic pathways in the plants. While supply of these medicinally important molecules relies on extraction from the producing species, recent years have seen significant advances in metabolic engineering of microorganisms for the production of plant natural products. Escherichia coli and Saccharomyces cerevisiae are the two most widely used heterologous hosts for expression of enzymes and reconstitution of plant natural product biosynthetic pathways. Total biosynthesis of many plant polyketide natural products such as curcumin and piceatannol in microorganisms has been achieved. While the late biosynthetic steps of more complex molecules such as paclitaxel and artemisinin remain to be understood, reconstitution of their partial biosynthetic pathways and microbial production of key intermediates have been successful. This review covers recent advances in understanding and engineering the biosynthesis of plant polyketides and terpenoids in microbial hosts.

Multimodular type I polyketide synthases in algae evolve by module duplications and displacement of AT domains in trans.

BackgroundPolyketide synthase (PKS) catalyzes the biosynthesis of polyketides, which are structurally and functionally diverse natural products in microorganisms and plants. Here, we have analyzed available full genome sequences of microscopic and macroscopic algae for the presence of type I PKS genes.ResultsType I PKS genes are present in 15 of 32 analyzed algal species. In chlorophytes, large proteins in the MDa range are predicted in most sequenced species, and PKSs with free-standing acyltransferase domains (trans-AT PKSs) predominate. In a phylogenetic tree, PKS sequences from different algal phyla form clades that are distinct from PKSs from other organisms such as non-photosynthetic protists or cyanobacteria. However, intermixing is observed in some cases, for example polyunsaturated fatty acid (PUFA) and glycolipid synthases of various origins. Close relationships between type I PKS modules from different species or between modules within the same multimodular enzyme were identified, suggesting module duplications during evolution of algal PKSs. In contrast to type I PKSs, nonribosomal peptide synthetases (NRPSs) are relatively rare in algae (occurrence in 7 of 32 species).ConclusionsOur phylogenetic analysis of type I PKSs in algae supports an evolutionary scenario whereby integrated AT domains were displaced to yield trans-AT PKSs. Together with module duplications, the displacement of AT domains may constitute a major mechanism of PKS evolution in algae. This study advances our understanding of the diversity of eukaryotic PKSs and their evolutionary trajectories.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2222-9) contains supplementary material, which is available to authorized users.

The Sound of Silence: Activating Silent Biosynthetic Gene Clusters in Marine Microorganisms.

Unlocking the rich harvest of marine microbial ecosystems has the potential to both safeguard the existence of our species for the future, while also presenting significant lifestyle benefits for commercial gain. However, while significant advances have been made in the field of marine biodiscovery, leading to the introduction of new classes of therapeutics for clinical medicine, cosmetics and industrial products, much of what this natural ecosystem has to offer is locked in, and essentially hidden from our screening methods. Releasing this silent potential represents a significant technological challenge, the key to which is a comprehensive understanding of what controls these systems. Heterologous expression systems have been successful in awakening a number of these cryptic marine biosynthetic gene clusters (BGCs). However, this approach is limited by the typically large size of the encoding sequences. More recently, focus has shifted to the regulatory proteins associated with each BGC, many of which are signal responsive raising the possibility of exogenous activation. Abundant among these are the LysR-type family of transcriptional regulators, which are known to control production of microbial aromatic systems. Although the environmental signals that activate these regulatory systems remain unknown, it offers the exciting possibility of evoking mimic molecules and synthetic expression systems to drive production of potentially novel natural products in microorganisms. Success in this field has the potential to provide a quantum leap forward in medical and industrial bio-product development. To achieve these new endpoints, it is clear that the integrated efforts of bioinformaticians and natural product chemists will be required as we strive to uncover new and potentially unique structures from silent or cryptic marine gene clusters.

Recent advances in awakening silent biosynthetic gene clusters and linking orphan clusters to natural products in microorganisms

Secondary metabolites from microorganisms have a broad spectrum of applications, particularly in therapeutics. The growing number of sequenced microbial genomes has revealed a remarkably large number of natural product biosynthetic clusters for which the products are still unknown. These cryptic clusters are potentially a treasure house of medically useful compounds. The recent development of new methodologies has made it possible to begin unlock this treasure house, to discover new natural products and to determine their biosynthesis pathways. This review will highlight some of the most recent strategies to activate silent biosynthetic gene clusters and to elucidate their corresponding products and pathways.

Modular biocatalysts

AbstractModularity is a highly sought after feature in engineering design. A modular catalyst is a multi‐component system whose parts can be predictably interchanged for functional flexibility and variety. Over the past two decades, much of the research in our laboratory has focused on understanding the modularity of a class of multifunctional enzymes called polyketide synthases (PKSs). PKSs catalyze the biosynthesis of a broad range of complex natural products in microorganisms, including many well‐known and emerging antibiotics. A better understanding of the fundamental principles governing their modular chemistry promises to create powerful opportunities for engineering new medicines, and may even open the door to radically new catalytic processes for functionally dense, chiral synthons. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Efficientin VivoSynthesis and Rapid Purification of Chorismic Acid Using an EngineeredEscherichia coliStrain

Chorismate is a key intermediate in the biosynthesis of aromatic amino acids and other natural products in microorganisms and plants. Four chorismate mutase-deficient strains ofEscherichia coliwere evaluated for the large scale microbiological production of this metabolite which is needed for detailed biochemical and structural studies of chorismate-utilizing enzymes. Optimization of culturing and isolation conditions with one of these strains yielded an improved protocol for the production of chorismate in yields that compare favorably with those previously obtained withKlebsiella pneumoniaestrain 62-1, a Class 2 pathogenic organism. A simple, single-step procedure for the purification of large quantities of chorismic acid by C18 reverse phase silica gel flash chromatography is also described. Chorismic acid obtained through this procedure is 90–98% pure and can be stored as the free acid in crystalline form over several months without decomposition.