Abstract:

Abstract:Marine-derived fungi were the main source of marine microbial natural products (NPs) due to their complex genetic background, chemodiversity and high yield of NPs. According to our previous survey for marine microbial NPs from 2010 to 2013, Aspergillus fungi have received the most of attention among all the marine-derived fungi, which accounted for 31% NPs of the marine fungal origins. This paper reviewed the sources, chemical structures and bioactivites of all the 512 new marine NPs of Aspergillus fungal origins from 1992 to 2014. These marine NPs have diverse chemical structures including polyketides, fatty acids, sterols and terpenoids, alkaloids, peptides, and so on, 36% of which displayed bioactivities such as cytotoxicity, antimicrobial activity, antioxidant and insecticidal activity. Nitrogen compounds are the major secondary metabolites accounting for 52% NPs from the marine-derived Aspergillus fungi. Nitrogen compounds are also the class with the highest ratio of bioactive compounds, 40% of which are bioactive. Plinabulin, a dehydrodiketopiperazine derivative of halimide had been ended its phase II trial and has received its phase III study from the third quarter of 2015 for the treatment of advanced, metastatic non-small cell lung cancer.

Abstract:Streptothricins are a group of the earliest discovered antibiotics with broad antimicrobial spectrum, and have been used for crop protection. We reviewed the studies on streptothricin resistance, biosynthesis of the three components (streptolidine, carbamoylated D-glucosamine and poly β-lysine chain) and chemical synthesis of streptothricins. The important aspects for future streptothricin researches were also discussed.

Abstract:Lanthipeptides are a growing class of ribosomally synthesized and posttranslationally modified peptide (RiPP) natural products. These compounds are widely distributed among taxonomically distant species, and their structures and biological activities are diverse, providing an important source for drug research and developement. In this review, we summarized the recent advances in the understanding of structure, classification, evolution and substrate-controlled biosynthetic mechanism of lanthipeptide, attempting to highlight the intriguing chemistry and enzymology in the biosynthesis of this growing family of natural products.

Abstract:Dithiolopyrrolones are a family of antibiotics that possess the unique pyrrolinonodithiole (4H-[1, 2] dithiolo [4, 3-b] pyrrol-5-one) skeleton. This family of natural products can be divided into three subfamilies: N-methyl-Nacylpyrrothine, N-acylpyrrothine and thiomarinols. So far, more than 27 members of this group of natural products have been reported including the well-known antibiotics holomycin, thiolutin, aureothricin and recently isolated thiomarinols. Dithiolopyrrolones exhibit relatively broad-spectrum antibiotic activities against many Gram-positive, Gram-negative bacteria and parasites. Some dithiolopyrrolones even have antitumor activities. In recent years, several dithiolopyrrolone biosynthetic gene clusters have been reported and their biosynthetic mechanisms have also been intensively studied. This review will give an overview about the biosynthesis and metabolic engineering of the dithiolopyrrolone natural products, and provides references to guide the creation of hybrid "unnatural" dithiolopyrrolones with better bioactivity and low toxicity by synthetic biology.

Abstract:Spinosad, extracted from Saccharopolyspora spinosa, one of the most successful commercial bioinsecticides, is derived from a family of macrocyclic lactones. It shows excellent potent insecticidal activities, low residue, and low environmental effect. Here, we reviewed the biosynthetic pathway of spinosad, the chemoenzymatic method of spinosad synthesis, and the strain improvement method and the heterologous expression of spinosad.

Abstract:[Objective] To determine the functions of gouC and gouD in gougerotin biosynthesis, disruption of these two genes was performed. As gougerotin producing strain Streptomyces graminearus lacks efficient genetic manipulation system, the gene cluster for gougerotin biosynthesis was heterologously expressed in Streptomyces coelicolor M1146 to facilitate genetic manipulations of gouC and gouD. [Methods] By using fosmid D6-4H containing the complete gougerotin biosynthetic gene cluster, gouC and gouD were disrupted by PCR-targeting method to generate pGOUe-ΔC and pGOUe-ΔD. Both pGOUe-ΔC and pGOUe-ΔD were introduced into Streptomyces coelicolor M1146 by intergeneric conjugation, thus gouC and gouD disrpution mutants (M1146-GOUe-ΔC and M1146-GOUe-ΔD) were obtained. The gougerotin production of M1146-GOUe-ΔC and M1146-GOUe-ΔD were assayed by HPLC analysis. The intermediates accumulated in these mutants were purified and subjected to MS and NMR analyses for structure determinations. Bioassay of these intermediates against tumor cell line were also carried out. [Results] Disruption mutants of gouC and gouD failed to produce gougerotin and the mutants accumulated different gougerotin intermediates, which lost their ability to inhibit cancer cell proliferation. [Conclusion] gouC and gouD are key structual genes in the biosynthesis of gougerotin peptidyl moieties. This study will pave the way for the elucidation of gougerotin biosynthetic pathway.

Abstract:Polyketides represent an important class of structurally and functionally diverse secondary metabolites with high economic value. Among bacteria, Streptomycetes are the main producers of polyketides. To enhance polyketide production in Streptomyces hosts, rational metabolic engineering approaches have been applied, such as overexpressing rate-limiting enzymes, or transcriptional activator, increasing the supply of precursor, removing feedback inhibition by end products and heterologous expression of polyketide biosynthetic gene clusters. In this review, we discuss examples of successful metabolic engineering strategies used to improve polyketide production in Streptomycetes. Meanwhile, we also address future prospective, emerging synthetic biology strategies to dynamically adjust the metabolic fluxes of pathways related to polyketide synthesis.

Abstract:Fungal products are important resources for natural drugs. Availabilities of many fungal genome sequences indicate that fungi have the huge potential to produce secondary metabolites. However, many valuable fungal natural products are hard to obtain under regular lab conditions because fungi are slow to grow, difficult to genetically modify, or have low yield of desired metabolites. Therefore, developing a heterologous expression system has been an efficient approach to discover novel natural product and elucidate the complicated biosynthetic pathways. This review describes several heterologous expression systems that have been successfully used for the expression of fungal biosynthetic gene clusters. Also, we address the application perspective based on the emerging DNA assembly technologies.

Abstract:Natural products and their derivatives play an important role in modern healthcare. Their diversity in bioactivity and chemical structure inspires scientists to discover new drug entities for clinical use. However, chemical synthesis of natural compounds has insurmountable difficulties in technology and cost. Also, many original-producing bacteria have disadvantages of needing harsh cultivation conditions, having low productivity and other shortcomings. In addition, some gene clusters responsible for secondary metabolite biosynthesis are silence in the original strains. Therefore, it is of great significance to exploit strategy for the heterologous expression of natural products guided by synthetic biology. Recently, researchers pay more attention on using actinomycetes that are the main source of many secondary metabolites, such as antibiotics, anticancer agents, and immunosuppressive drugs. Especially, with huge development of genome sequencing, abundant resources of natural product biosynthesis in Streptomyces have been discovered, which highlight the special advantages on developing Streptomyces as the heterologous expression chassis cells. This review begins with the significance of the development of Streptomyces chassis, focusing on the strategies and the status in developing Streptomyces chassis cells, followed by examples to illustrate the practical applications of a variety of Streptomyces chassis.

Abstract:Microbial drug is a large family of small molecules with unusual structural features and potent bioactivities. The production of microbial drug is crucial for its subsequent development and cost. Traditional breeding strategies for microbial drug production have been demonstrated to be remarkably effective, but they have also indicated the drawback of exceptional randomness and high cost. Synthetic biology has recently promised a revival for the rational enhancement of microbial drugs. In this review, we mainly discuss the recent progress from the aspects of promoter engineering, precursor supply, genome shuffling and etc., to delineate the application of the synthetic biology strategies to enhance the production of the microbial drugs, particularly, produced by actinomycetes.

Abstract:The beta-lactam antibiotic cephalosporin C is produced industrially by Acremonium chrysogenum. Its derivative 7-aminocephalosporanic acid (7-ACA) is the intermediate of most chemical modification cephalosporins that are the most frequently used antibiotics for the therapy of infectious diseases. Due to its importance, the biosynthetic pathway of cephalosporin C has been elucidated in Acremonium chrysogenum. To improve the yield of cephalosporin C and reduce the cost of production, recent studies have been focused on the sophisticated regulation of cephalosporin C biosynthesis. In this review, recent advances in cephalosporin C biosynthesis and regulation are summarized.

Abstract:[Objective] We investegated the role of extracytoplasmic function (ECF) σ factor, σ⁵, in avermectin biosynthesis, morphological differentiation and stress response in S. avermitilis. [Methods] We constructed sig5 gene deletion, complementation and overexpression strains and determined the role of σ⁵ in avermectin production and morphological differentiation by shaking flask fermentation and morphological observation of these strains. We used RT-qPCR, EMSA and ChIP assays to identify the target genes of σ⁵. We used stress tests to reveal the stress response that σ⁵ may be involved in. [Results] Determination of avermectin production and morphological observation in sig5 related strains implied that σ⁵ inhibits avermectin production, but has no effect on growth or morphology. Deletion of sig5 increased transcription levels of pathway-specific activator gene aveR and structural gene aveA1, but σ⁵ did not bind to the promoter regions of aveR and aveA1. RT-qPCR and ChIP assays showed that σ⁵ positively regulates the transcription of itself and adjacent genes by binding to the promoter regions of sig5, SAV612, SAV615 and SAV618. Stress tests suggested that σ⁵ is involved in responding to osmotic stress. [Conclusion] Our findings indicated that σ⁵ indirectly inhibits avermectin production by affecting transcription of ave genes.

Abstract:[Objective] The study aimed to determine the appropriate stage for exploring the response of Bacillus thuringiensis to the alkaline stress, to profile the metabolic pathways under this stress. [Methods] Using semiquantitative RT-PCR and qRT-PCR, the proper stage was defined by monitoring the transcriptional changes of marker gene pspA, which was known as a responsive gene under the alkaline stress. The total RNA was then extracted to perform the microarray hybridizations for samples under stress and control, respectively. Gene Ontology and pathway enrichments were conducted to analyze the global changes of carbon metabolism, metabolism of fatty acid synthesis and amino acid. [Results] For B. thuringiensis in the mid-log growth phase, treatment of 28 mmol/L NaOH for 10 mins is the feasible approach to analyze the response of B. thuringiensis to this stress. More than twenty genes encoding important enzymes in glycolytic pathway were up-regulated and majority of genes involved in catalyzing alpha-ketoglutarate into malic acid were also found to up-regulated more than two folds. [Conclusion] By analyzing the gene expression profile, the major metabolisms of B. thuringiensis were found to be clearly enhanced under alkaline stress. Large quantities of acid including malic acid and lactic acid may contribute a lot to the adaptation of alkaline condition.

Abstract:Cytochrome P450 enzymes broadly exist in animals, plants and microorganisms. This superfamily of monooxygenases holds the greatest diversity of substrate structures and catalytic reaction types among all enzymes. P450 enzymes play important roles in natural product biosynthesis. In particular, P450 enzymes are capable of catalyzing the regio-and stereospecific oxidation of non-activated C-H bonds in complex organic compounds under mild conditions, which overrides many chemical catalysts. This advantage thus warrants their great potential in microbial drug development. In this review, we introduce a variety of P450 enzymes involved in natural product biosynthesis; provide a brief overview on protein engineering, biotransformation and practical application of P450 enzymes; and discuss the limits, challenges and prospects of industrial application of P450 enzymes.

Abstract:Plant-derived natural products (PNPs) have been widely used in pharmaceutical and nutritional fields. So far, the main method to produce PNPs is extracting them from their original plants, however, there remains lots of problems. With the concept of synthetic biology, construction of yeast cell factories for production of PNPs provides an alternative way. In this review, we will focus on PNPs' market and application, research progress for production of artemisinin, research progress for production of terpenes, alkaloids and polyunsaturated fatty acid (PUFAs) and recent technology development to give a brief introduction of construction of yeast cells for production of PNPs.

Abstract:Cell-free protein synthesis (CFPS) systems have been widely used for decades as a rapid and efficient tool in fundamental biology. Without the requirements for cell viability and growth, CFPS systems have distinct advantages over in vivo systems for protein production. Recently, great efforts have been made to further optimize CFPS systems to produce proteins at high yields, reduced cost and increased scale, including simplifying extract preparation procedures, developing new energy regeneration systems to protein synthesis, stabilizing substrate supply and promoting protein folding. Nowadays, CFPS systems are emerging as a powerful platform for industrial and highthroughput production of protein therapeutics, providing an alternative solution to solve problems in biopharmaceutical engineering. Moreover, CFPS systems have been successfully applied to high-throughput drug screening, large-scale protein therapeutics production, custom-made anti-cancer vaccines. These achievements highlight that CFPS systems have great potential for a wide range of applications in biopharmaceutical engineering in the future.

Abstract:The uprise of the superpower nations is always accompanied by the breakthrough and advances of technologies and innovations in the history. Natural products play very important role in human health, such as anticancer molecular taxol, anti-infection drug artemisinin that save a lot of lives, metabolic disease treatment, nutrition and health care. However, more has never been explored. With the 2015 Nobel Prize in Physiology or Medicine awarded to William C. Campbell, Satoshi Ōmura, and Youyou Tu for the discovery of avermectins and artemisinin respectively, the second “Golden age” in the development of natural product is dawning. China is a “world factory” and natural drugs-rich country, but how to upgrade and advance the industry and realize the China dream? Avermectins, produced by Streptomyces avermitilis, are pesticide with high efficiency and low levels of side effects. However, the low producer and expensive development pattern of high consumption, high contamination is not sustainable. Solving the problem, increasing the production and utilization of raw material, reducing the energy consumption and cost of production, decreasing environmental pollution are key to transform China into a power house. In this paper, we case-study avermectins to review the industry development driven by fundamental research. Institute of Microbiology, Chinese Academy of Sciences increased the production of avermectin 1000 folds to 9 g/L, which out licensed to new Veyong biochemical Ltd and avermectin Coalitions. As a result, Merck Sharp and Dohme ceased the manufacture of avermectins. The success also shed lights on the improvement of other natural product drugs in China.