Stepwise increase of fidaxomicin in an engineered heterologous host through multi-level metabolic engineering.

The anti- infection (CDI) drug fidaxomicin is a natural polyketide metabolite mainly produced by , such as , , and . In the present study, we employed a stepwise strategy by combining heterologous expression, chassis construction, promoter engineering, activator and transporters overexpression, and optimization of fermentation media for high-level production of fidaxomicin. The maximum yield of 384 mg/L fidaxomicin was achieved with engineered D7-VHb in 5 L-tank bioreactor, and it was approximately 15-fold higher than the native strain YP-1 with higher strain stability and growth rate.

Degradation mechanism of AtrA mediated by ClpXP and its application in daptomycin production in Streptomyces roseosporus.

The efficiency of drug biosynthesis depends on different transcriptional regulatory pathways in Streptomyces, and the protein degradation system adds another layer of complexity to the regulatory processes. AtrA, a transcriptional regulator in the A-factor regulatory cascade, stimulates the production of daptomycin by binding to the dptE promoter in Streptomyces roseosporus. Using pull-down assays, bacterial two-hybrid system and knockout verification, we demonstrated that AtrA is a substrate for ClpP protease.

Improving the Yield and Quality of Daptomycin in by Multilevel Metabolic Engineering.

Daptomycin is a cyclic lipopeptide antibiotic with a significant antibacterial action against antibiotic-resistant Gram-positive bacteria. Despite numerous attempts to enhance daptomycin yield throughout the years, the production remains unsatisfactory. This study reports the application of multilevel metabolic engineering strategies in to reconstruct high-quality daptomycin overproducing strain L2797-VHb, including precursor engineering (i.

A novel strategy of gene screen based on multi-omics in Streptomyces roseosporus.

Daptomycin is a new lipopeptide antibiotic for treatment of severe infection caused by multi-drug-resistant bacteria, but its production cost remains high currently. Thus, it is very important to improve the fermentation ability of the daptomycin producer Streptomyces roseosporus. Here, we found that the deletion of proteasome in S.

Rational engineering strategies for achieving high-yield, high-quality and high-stability of natural product production in actinomycetes.

Actinomycetes are recognized as excellent producers of microbial natural products, which have a wide range of applications, especially in medicine, agriculture and stockbreeding. The three main indexes of industrialization (titer, purity and stability) must be taken into overall consideration in the manufacturing process of natural products. Over the past decades, synthetic biology techniques have expedited the development of industrially competitive strains with excellent performances.

Genome-based rational engineering of Actinoplanes deccanensis for improving fidaxomicin production and genetic stability.

Microbial fermentation is currently still the major way to produce structural complicated clinical drugs. Yet, the low productivity and genetic instability of producing strains remain the bottlenecks in microbial pharmaceutical industry. Fidaxomicin is a microbial drug against the Clostridium difficile infection.

Comprehensive dissection of dispensable genomic regions in Streptomyces based on comparative analysis approach.

Background: Large-scale genome reduction has been performed to significantly improve the performance of microbial chassis. Identification of the essential or dispensable genes is pivotal for genome reduction to avoid synthetic lethality. Here, taking Streptomyces as an example, we developed a combinatorial strategy for systematic identification of large and dispensable genomic regions in Streptomyces based on multi-omics approaches.

Activation of anthrachamycin biosynthesis in Streptomyces chattanoogensis L10 by site-directed mutagenesis of rpoB.

Genome sequencing projects revealed massive cryptic gene clusters encoding the undiscovered secondary metabolites in Streptomyces. To investigate the metabolic products of silent gene clusters in Streptomyces chattanoogensis L10 (CGMCC 2644), we used site-directed mutagenesis to generate ten mutants with point mutations in the highly conserved region of rpsL (encoding the ribosomal protein S12) or rpoB (encoding the RNA polymerase β-subunit). Among them, L10/RpoB (H437Y) accumulated a dark pigment on a yeast extract-malt extract-glucose (YMG) plate.

FadR1, a pathway-specific activator of fidaxomicin biosynthesis in Actinoplanes deccanensis Yp-1.

Fidaxomicin, an 18-membered macrolide antibiotic, is highly active against Clostridium difficile, the most common cause of diarrhea in hospitalized patients. Though the biosynthetic mechanism of fidaxomicin has been well studied, little is known about its regulatory mechanism. Here, we reported that FadR1, a LAL family transcriptional regulator in the fidaxomicin cluster of Actinoplanes deccanensis Yp-1, acts as an activator for fidaxomicin biosynthesis.

Rational construction of genome-reduced and high-efficient industrial Streptomyces chassis based on multiple comparative genomic approaches.

Background: Streptomyces chattanoogensis L10 is the industrial producer of natamycin and has been proved a highly efficient host for diverse natural products. It has an enormous potential to be developed as a versatile cell factory for production of heterologous secondary metabolites. Here we developed a genome-reduced industrial Streptomyces chassis by rational 'design-build-test' pipeline.

Transcriptome-Based Identification of a Strong Promoter for Hyper-production of Natamycin in Streptomyces.

Streptomyces are famed producers of secondary metabolites with diverse bioactivities and structures. However, biosynthesis of natural products will consume vast precursors from primary metabolism, and some secondary metabolites are toxic to the hosts. To overcome this circumstance and over-produce secondary metabolites, one of the strategies is to over-express biosynthetic genes under strong promoters specifically expressed during secondary metabolism.

Bidirectional Regulation of AdpA in Controlling the Expression of and in the Natamycin Biosynthesis of L10.

AdpA, an AraC/XylS family protein, had been proved as a key regulator for secondary metabolism and morphological differentiation in . Here, we identify AdpA, an ortholog of AdpA, as a "higher level" pleiotropic regulator of natamycin biosynthesis with bidirectional regulatory ability in L10. DNase I footprinting revealed six AdpA-binding sites in the - intergenic region.

Generation of the natamycin analogs by gene engineering of natamycin biosynthetic genes in Streptomyces chattanoogensis L10.

The polyene antibiotic natamycin is widely used as an antifungal agent in both human therapy and the food industry. Here we obtained four natamycin analogs with high titers, including two new compounds, by engineering of six post-polyketide synthase (PKS) tailoring enzyme encoding genes in a natamycin industrial producing strain, Streptomyces chattanoogensis L10. Precise analysis of S.

Sigma factor WhiGch positively regulates natamycin production in Streptomyces chattanoogensis L10.

The roles of many sigma factors are unclear in regulatory mechanism of secondary metabolism in Streptomyces. Here, we report the regulation network of a group 3 sigma factor, WhiGch, from a natamycin industrial strain Streptomyces chattanoogensis L10. WhiGch regulates the growth and morphological differentiation of S.

Transcriptome-guided identification of SprA as a pleiotropic regulator in Streptomyces chattanoogensis.

Quorum sensing molecular γ-butyrolactones (GBL) are widely distributed among the genus Streptomyces. Their cognate receptors have been demonstrated to control secondary metabolism and/or morphological differentiation. ScgA is responsible for the biosynthesis of GBL in Streptomyces chattanoogensis.

WblAch, a pivotal activator of natamycin biosynthesis and morphological differentiation in Streptomyces chattanoogensis L10, is positively regulated by AdpAch.

Detailed mechanisms of WhiB-like (Wbl) proteins involved in antibiotic biosynthesis and morphological differentiation are poorly understood. Here, we characterize the role of WblAch, a Streptomyces chattanoogensis L10 protein belonging to this superfamily. Based on DNA microarray data and verified by real-time quantitative PCR (qRT-PCR), the expression of wblAch was shown to be positively regulated by AdpAch.

[Beneficial effects of liver X receptor agonist on adipose-derived mesenchymal stem cells transplantation in mice with myocardial infarction].

Objective: To investigate the effects of liver X receptor (LXR) agonist on adipose-derived mesenchymal stem cells (AD-MSCs) implantation into infarcted hearts of mice.

Method: AD-MSC(Fluc+) which stably expressed firefly luciferase (Fluc) were isolated from β-actin-Fluc transgenic mice and characterized by flow cytometry. Male FVB mice were randomly allocated into the following four groups (n = 10 each): (1) sham group; (2) MI + PBS group; (3) MI + AD-MSC(Fluc+) group; (4) MI + AD-MSC(Fluc+) + LXR agonist (T0901317) group.

Tetrodotoxin attenuates isoproterenol-induced hypertrophy in H9c2 rat cardiac myocytes.

Cardiac hypertrophy is often associated with an increased sympathetic drive, and both in vitro and in vivo studies have demonstrated the development of cardiomyocyte hypertrophy in response to either α- or β- adrenergic stimulation. The present study was carried out to determine whether the reversible sodium channel blocker tetrodotoxin (TTX) exerts a direct anti-hypertrophic effect on isoproterenol (ISO)-induced cell hypertrophy and find the underlying mechanism that regulate [Na(+)]( i ). The experiments were performed on cultured H9c2 cells exposed to ISO (10 μM) alone or combined with TTX (1 μM) for 48 h.