Streptomyces sp. BV410 isolate from chamomile rhizosphere soil efficiently produces staurosporine with antifungal and antiangiogenic properties

A JAGN1-associated severe congenital neutropenia zebrafish model revealed an altered G-CSFR signaling and UPR activation

ABSTRACT

A variety of autosomal recessive mutations in the JAGN1 gene cause severe congenital neutropenia (CN). However, the underlying pathomechanism remains poorly understood, mainly because of the limited availability of primary hematopoietic stem cells from JAGN1-CN patients and the absence of animal models. In this study, we aimed to address these limitations by establishing a zebrafish model of JAGN1-CN. We found 2 paralogs of the human JAGN1 gene, namely jagn1a and jagn1b, which play distinct roles during zebrafish hematopoiesis. Using various approaches such as morpholino-based knockdown, CRISPR/Cas9-based gene editing, and misexpression of a jagn1b harboring a specific human mutation, we successfully developed neutropenia while leaving other hematopoietic lineages unaffected. Further analysis of our model revealed significant upregulation of apoptosis and genes involved in the unfolded protein response (UPR). However, neither UPR nor apoptosis is the primary mechanism that leads to neutropenia in zebrafish. Instead, Jagn1b has a critical role in granulocyte colony-stimulating factor receptor signaling and steady-state granulopoiesis, shedding light on the pathogenesis of neutropenia associated with JAGN1 mutations. The establishment of a zebrafish model for JAGN1-CN represents a significant advancement in understanding the specific pathologic pathways underlying the disease. This model provides a valuable in vivo tool for further investigation and exploration of potential therapeutic strategies.

Late-stage diversification of bacterial natural products through biocatalysis

Bacterial natural products (BNPs) are very important sources of leads for drug development and chemical novelty. The possibility to perform late-stage diversification of BNPs using biocatalysis is an attractive alternative route other than total chemical synthesis or metal complexation reactions. Although biocatalysis is gaining popularity as a green chemistry methodology, a vast majority of orphan sequenced genomic data related to metabolic pathways for BNP biosynthesis and its tailoring enzymes are underexplored. In this review, we report a systematic overview of biotransformations of 21 molecules, which include derivatization by halogenation, esterification, reduction, oxidation, alkylation and nitration reactions, as well as degradation products as their sub-derivatives. These BNPs were grouped based on their biological activities into antibacterial (5), antifungal (5), anticancer (5), immunosuppressive (2) and quorum sensing modulating (4) compounds. This study summarized 73 derivatives and 16 degradation sub-derivatives originating from 12 BNPs. The highest number of biocatalytic reactions was observed for drugs that are already in clinical use: 28 reactions for the antibacterial drug vancomycin, followed by 18 reactions reported for the immunosuppressive drug rapamycin. The most common biocatalysts include oxidoreductases, transferases, lipases, isomerases and haloperoxidases. This review highlights biocatalytic routes for the late-stage diversification reactions of BNPs, which potentially help to recognize the structural optimizations of bioactive scaffolds for the generation of new biomolecules, eventually leading to drug development.

Bioactive Metabolites from Terrestrial and Marine Actinomycetes

Actinomycetes inhabit both terrestrial and marine ecosystems and are highly proficient in producing a wide range of natural products with diverse biological functions, including antitumor, immunosuppressive, antimicrobial, and antiviral activities. In this review, we delve into the life cycle, ecology, taxonomy, and classification of actinomycetes, as well as their varied bioactive metabolites recently discovered between 2015 and 2023. Additionally, we explore promising strategies to unveil and investigate new bioactive metabolites, encompassing genome mining, activation of silent genes through signal molecules, and co-cultivation approaches. By presenting this comprehensive and up-to-date review, we hope to offer a potential solution to uncover novel bioactive compounds with essential activities.

Streptomyces sp. BV410: Interspecies cross-talk for staurosporine production

AIMS

Sequencing and genome analysis of two co-isolated streptomycetes, named BV410-1 and BV410-10, and the effect of their co-cultivation on the staurosporine production.

METHODS AND RESULTS

Identification of two strains through genome sequencing and their separation using different growth media was conducted. Sequence analysis revealed that the genome of BV410-1 was 9.5 Mb, whilst that of BV410-10 was 7.1 Mb. AntiSMASH analysis identified 28 biosynthetic gene clusters (BGCs) from BV410-1, including that responsible for staurosporine biosynthesis, whilst 20 BGCs were identified from BV410-10. The addition of cell-free supernatant from BV410-10 monoculture to BV410-1 fermentations improved the staurosporine yield from 8.35 mg L^-1 up to 15.85 mg L^-1 , whilst BV410-10 monoculture ethyl acetate extract did not have the same effect. Also, there was no improvement in staurosporine production when artificial mixed cultures were created using three different BV410-1 and BV410-10 spore ratios.

CONCLUSIONS

The growth of BV410-10 was inhibited when the two strains were grown together on agar plates. Culture supernatants of BV410-10 showed potential to stimulate staurosporine production in BV410-1, but overall co-cultivation attempts did not restore the previously reported yield of staurosporine produced by the original mixed isolate.

SIGNIFICANCE AND IMPACT OF STUDY

This work confirmed complex relations between streptomycetes in soil that are difficult to recreate under the laboratory conditions. Also, mining of streptomycetes genomes that mainly produce known bioactive compounds could still be the fruitful approach in search for novel bioactive molecules.

Streptomyces sp. BV410 isolate from chamomile rhizosphere soil efficiently produces staurosporine with antifungal and antiangiogenic properties

Applying a bioactivity‐guided isolation approach, staurosporine was separated and identified as the active principle in the culture extract of the new isolate Streptomyces sp. BV410 collected from the chamomile rhizosphere. The biotechnological production of staurosporine by strain BV410 was optimized to yield 56 mg/L after 14 days of incubation in soy flour–glucose–starch–mannitol‐based fermentation medium (JS). The addition of FeSO₄ significantly improved the staurosporine yield by 30%, while the addition of ZnSO₄ significantly reduced staurosporine yield by 62% in comparison with the starting conditions. Although staurosporine was first isolated in 1977 from Lentzea albida (now Streptomyces staurosporeus) and its potent kinase inhibitory effect has been established, here, the biological activity of this natural product was assessed in depth in vivo using a selection of transgenic zebrafish (Danio rerio) models, including Tg(fli1:EGFP) with green fluorescent protein‐labeled endothelial cells allowing visualization and monitoring of blood vessels. This confirmed a remarkable antiangiogenic activity of the compound at doses of 1 ng/ml (2.14 nmol/L) which is below doses inducing toxic effects (45 ng/ml; 75 nmol/L). A new, efficient producing strain of commercially significant staurosporine has been described along with optimized fermentation conditions, which may lead to optimization of the staurosporine scaffold and its wider applicability.