Ribosomally derived lipopeptides containing distinct fatty acyl moieties

Lipopeptides represent a large group of microbial natural products that include important antibacterial and antifungal drugs and some of the most-powerful known biosurfactants. The vast majority of lipopeptides comprise cyclic peptide backbones N-terminally equipped with various fatty acyl moieties. The known compounds of this type are biosynthesized by nonribosomal peptide synthetases, giant enzyme complexes that assemble their products in a non–gene-encoded manner. Here, we report the genome-guided discovery of ribosomally derived, fatty-acylated lipopeptides, termed selidamides. Heterologous reconstitution of three pathways, two from cyanobacteria and one from an arctic, ocean-derived alphaproteobacterium, allowed structural characterization of the probable natural products and suggest that selidamides are widespread over various bacterial phyla. The identified representatives feature cyclic peptide moieties and fatty acyl units attached to (hydroxy)ornithine or lysine side chains by maturases of the GCN5-related N-acetyltransferase superfamily. In contrast to nonribosomal lipopeptides that are usually produced as congener mixtures, the three selidamides are selectively fatty acylated with C10, C12, or C16 fatty acids, respectively. These results highlight the ability of ribosomal pathways to emulate products with diverse, nonribosomal-like features and add to the biocatalytic toolbox for peptide drug improvement and targeted discovery.

Biosynthesis of C-nucleoside antibiotics in actinobacteria: recent advances and future developments

Epidemic diseases and antibiotic resistance are urgent threats to global health, and human is confronted with an unprecedented dilemma to conquer them by expediting development of new natural product related drugs. C-nucleoside antibiotics, a remarkable group of microbial natural products with diverse biological activities, feature a heterocycle base linked with a ribosyl moiety via an unusual C-glycosidic bond, and have played significant roles in healthcare and for plant protection. Elucidating how nature biosynthesizes such a group of antibiotics has provided the basis for engineered biosynthesis as well as targeted genome mining of more C-nucleoside antibiotics towards improved properties. In this review, we mainly summarize the recent advances on the biosynthesis of C-nucleoside antibiotics, and we also tentatively discuss the future developments on rationally accessing C-nucleoside diversities in a more efficient and economical way via synthetic biology strategies.

Engineering Aspergillus oryzae for the Heterologous Expression of a Bacterial Modular Polyketide Synthase

Microbial natural products have had phenomenal success in drug discovery and development yet form distinct classes based on the origin of their native producer. Methods that enable metabolic engineers to combine the most useful features of the different classes of natural products may lead to molecules with enhanced biological activities. In this study, we modified the metabolism of the fungus Aspergillus oryzae to enable the synthesis of triketide lactone (TKL), the product of the modular polyketide synthase DEBS1-TE engineered from bacteria. We established (2S)-methylmalonyl-CoA biosynthesis via introducing a propionyl-CoA carboxylase complex (PCC); reassembled the 11.2 kb DEBS1-TE coding region from synthetic codon-optimized gene fragments using yeast recombination; introduced bacterial phosphopantetheinyltransferase SePptII; investigated propionyl-CoA synthesis and degradation pathways; and developed improved delivery of exogenous propionate. Depending on the conditions used titers of TKL ranged from <0.01–7.4 mg/L. In conclusion, we have demonstrated that A. oryzae can be used as an alternative host for the synthesis of polyketides from bacteria, even those that require toxic or non-native substrates. Our metabolically engineered A. oryzae may offer advantages over current heterologous platforms for producing valuable and complex natural products.

Screening of Microbial Natural Products and Biological Evaluation of Trichomicin as Potential Anti-Cytokine Storm Agents

COVID-19 has remained an uncontained, worldwide pandemic. Most of the infected people had mild symptoms in the early stage, and suddenly worsened or even died in the later stage which made the cytokine release syndrome (CRS) once again aroused people’s attention. CRS is an excessive immunity of the body to external stimuli such as viruses, bacteria, and nanomaterials, which can cause tissue damage, local necrosis or even death. Lipopolysaccharide (LPS) is one of the most effective CRS inducers, which can activate macrophages to release cytokines, including tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL- 6 and chemokines. We used RT-PCR to detect the expression of representative cytokines in mouse and human cells at different concentrations of Trichomicin, Ebosin, and 1487B after LPS stimulation. The results showed that the expression of TNF-α, IL-1β, IL-6, and CXCL10 all increased after LPS stimulation. Among the various drugs, Trichomicin had the most obvious inhibitory effect on cytokine expression in vitro, and it was further verified in vivo that Trichomicin can improve the survival rate of mice stimulated with LPS. Finally, it was proved that Trichomicin inhibited the Stat3 and NF-κB pathways and reduced the phosphorylation of Stat3 and p65 after LPS stimulation, thereby inhibiting the response of macrophages to pro-inflammatory stimuli. The article clarified the inhibitory activity and mechanism of action of Trichomicin on CRS, and laid the foundation for the research on the anti-cytokine storm activity of microbial natural products.

Towards the production of tikitericin: A novel peptide from Thermogemmatispora strain T81

<p>The utilisation of natural products for treatment of human ailments has been rooted in various cultures for centuries. Extraction of natural products has been essential for the discovery of new drugs and inspiration for synthetic analogues. Since the success of penicillin, microbial natural products have been of interest. Genome mining of Thermogemmatisporastrain T81, a thermophile from the Taupo Volcanic Zone, found the potential for the production of novel ribosomally synthesised and post-translationally modified peptides (RiPPs). Previous work showed that T81 exhibited antimicrobial activity against a wide variety of extremophillic bacteria. Although the three thiopeptides encoded forin the genome of T81 have not been found, the lanthipeptide tikitericin has recently been isolated and described. Unfortunately tikitericin is produced in low quantities by T81 andbioactivity data has not yet been obtained. Because of its potential antimicrobial activity, different routes to produce it are of interest. The aim of this project wasto synthesisetikitericin by solid phase peptide synthesis. MS imaging was also utilised to search for the presence of tikitericin as an antimicrobial agent in situ.</p>

Towards the production of tikitericin: A novel peptide from Thermogemmatispora strain T81

<p>The utilisation of natural products for treatment of human ailments has been rooted in various cultures for centuries. Extraction of natural products has been essential for the discovery of new drugs and inspiration for synthetic analogues. Since the success of penicillin, microbial natural products have been of interest. Genome mining of Thermogemmatisporastrain T81, a thermophile from the Taupo Volcanic Zone, found the potential for the production of novel ribosomally synthesised and post-translationally modified peptides (RiPPs). Previous work showed that T81 exhibited antimicrobial activity against a wide variety of extremophillic bacteria. Although the three thiopeptides encoded forin the genome of T81 have not been found, the lanthipeptide tikitericin has recently been isolated and described. Unfortunately tikitericin is produced in low quantities by T81 andbioactivity data has not yet been obtained. Because of its potential antimicrobial activity, different routes to produce it are of interest. The aim of this project wasto synthesisetikitericin by solid phase peptide synthesis. MS imaging was also utilised to search for the presence of tikitericin as an antimicrobial agent in situ.</p>

Vertical Inheritance Facilitates Interspecies Diversification in Biosynthetic Gene Clusters and Specialized Metabolites

Microbial natural products are traditionally exploited for their pharmaceutical potential, yet our understanding of the evolutionary processes driving BGC evolution and compound diversification remains poorly developed. While HGT is recognized as an integral driver of BGC distributions, we find that the effects of vertical inheritance on BGC diversification had direct implications for species-level specialized metabolite production.

Qualitative and Quantitative Comparison of Liquid–Liquid Phase Extraction Using Ethyl Acetate and Liquid–Solid Phase Extraction Using Poly-Benzyl-Resin for Natural Products

A key step in the process of isolating microbial natural products is the preparation of an extract from a culture. This step determines which molecules will be available for detection in the subsequent chemical and biological analysis of a biodiscovery pipeline. In the present study we wanted to document potential differences in performance between liquid–liquid extraction using ethyl acetate and liquid–solid extraction using a poly-benzyl-resin. For the comparison of the two extraction protocols, we spiked a culture of Flavobacterium sp. with a diverse selection of natural products of microbial and plant origin to investigate whether the methods were comparable with respect to selectivity. We also investigated the efficiency of the two extraction methods quantitatively, using water spiked with a selection of natural products, and studied the quantitative effect of different pH levels of the aqueous solutions on the extraction yields of the two methods. The same compounds were extracted by the two methods, but the solid-phase extract contained more media components compared with the liquid-phase extract. Quantitatively, the two extraction methods varied in their recovery rates. We conclude that practical aspects could be more important when selecting one of the extraction protocols, as their efficiencies in extracting specific compounds were quite similar.

Isolation and identification of marine microbial products

Background The ocean is one of the world’s most important sources of bioactive chemicals in the marine environment. Microbiologists, ecologists, agronomists, taxonomists, and evolutionary biologists have been increasingly interested in marine microbial natural products (MMNPs) in recent decades. Main body Diverse marine bacteria appear to get the ability to manufacture an astounding diversity of MMNPs with a wide range of biological actions, including anti-tumor, antimicrobial, and anti-cardiovascular agents according to numerous studies. Short conclusions Innovative isolation and culture methodologies, tactics for identifying novel MMNPs via routine screens, metagenomics, genomics, combinatorial biosynthesis, and synthetic biology are all discussed in this review. There is also a discussion of potential issues and future directions for studying MMNPs.