Biology subjects

Sokolova, N.

Publications and source records attributed to Sokolova, N..

8 recordsLinked to original sources

bioRxiv2026

Bidirectional interactions between gut microbiota and fluorochemical biotransformation and bioactivity

Fluorinated chemicals are increasingly prevalent in pharmaceuticals and agrochemicals, yet their influence on the human gut microbiome and the potential for microbial biotransformation to alter therapeutic and toxicological profiles remain poorly understood. Here, we investigated the bidirectional relationship between 15 structurally diverse fluorinated chemicals and the gut microbiota by using an ex vivo high-throughput fermentation system. Screening revealed that flutamide, fluazinam, and pretomanid were consistently biotransformed across the donor microbiomes, while other compounds showed substantial inter-individual variability in degradation. Furthermore, exposure to fluorinated chemicals induced compound-specific shifts in microbial diversity and community composition, demonstrating their capacity to alter gut microbial ecology. Using a computational workflow combining in silico biotransformation predictions with untargeted LC-MS/MS analysis, we identified nitroreduction as the primary gut microbial transformation across all three compounds. Single-strain experiments confirmed that the nitroreduction of flutamide to flu-6, previously attributed only to hepatic metabolism, is a widespread capacity among gut bacterial strains. Finally, in vitro cytotoxicity assays and in silico modelling further revealed flu-6 to be a less hepatotoxic derivative than the parent compound, suggesting a potential detoxifying role for the gut microbiota. Together, these findings establish an integrated ex vivo, in vitro, and in silico approach for assessing the bidirectional interactions between fluorinated chemicals and the gut microbiome.

pharmacology and toxicology↗

bioRxiv2024

A biocatalytic platform for the production of substituted 2-quinolones and (thio)coumarins

2-quinolones are privileged scaffolds for drug discovery that are relatively rare in nature. Here, we characterise two promiscuous fungal polyketide synthases AthePKS and FerePKS, which we had previously found to produce quinolones in vitro. We challenged the enzymes with several substituted anthranilic acid derivatives, revealing their ability to produce precursors of pharmaceutically relevant quinolones. We also discovered that AthePKS and FerePKS accept other 2-substituted benzoic acids, leading to the formation of coumarin and thiocoumarin scaffolds. We applied AthePKS in an artificial enzymatic cascade towards an antimicrobial 4-methoxy-1-methyl-2-quinolone and demonstrated its in vivo feasibility by successfully expressing the pathway in Escherichia coli. Lastly, we determined the crystal structure of AthePKS, suggesting hotspots for enhancing its catalytic efficiency by enzyme engineering. Our results provide a framework for further engineering of enzymatic routes towards privileged heteroaromatic scaffolds and derivatives thereof.

biochemistry↗

bioRxiv2024

Unravelling the functional diversity of type III polyketide synthases in fungi

Type III polyketide synthases (T3PKSs) are enzymes that produce diverse compounds of ecological and clinical importance. While well-studied in plants and bacteria, only a handful of T3PKSs from fungi have been characterised to date. Here, we developed a comprehensive workflow for kingdom-wide characterisation of T3PKSs. Using publicly available genomes, we mined more than 1000 putative enzymes and analysed their active site architecture and genomic neighbourhood. From there, we selected 37 representative PKS candidates for cell-free expression and prototyping with a diverse set of Coenzyme A activated substrates, revealing unique patterns in substrate and cyclisation specificity, as well as the preferred number of malonyl-Coenzyme A extensions. Using the 341 enzyme-substrate pairs generated in this study, we trained a machine learning model to predict T3PKS substrate specificity and experimentally validated it with an extended panel of non-natural substrates. We anticipate that the model will be useful for in silico screening of T3PKSs, while the insight into the product scope of these enzymes offers interesting starting points for further exploration.

biochemistry↗

bioRxiv2024

Discovery and heterologous expression of functional 4-O-dimethylallyl-L-tyrosine synthases from lichen-forming fungi.

Fungal DMATS-type aromatic prenyltransferases are a family of biosynthetic enzymes that catalyze the prenylation of a range of aromatic substrates during the biosynthesis of bioactive indole alkaloids, diketopiperazines, and meroterpenoids. Together with their broad substrate scope and soluble nature, this makes DMATS-type prenyltransferases particularly adept for applications in biocatalysis, for example to derivatize aromatic drug leads and improve their bioactivity. Here, we investigated four putative DMATS-type prenyltransferases from lichen-forming fungi, an underexplored group of organisms that produce more than 1,000 unique metabolites. We were able to successfully express two functional lichen prenyltransferases in the heterologous host A. oryzae, which allowed us to identify them as 4-O-dimethylallyltyrosine synthases. Our extensive bioinformatic analysis shows that related lichen prenyltransferases are likely not active on indoles but rather on aromatic polyketides and phenylpropanoids, common metabolites in these organisms. Overall, our work not only provides new insights into fungal DMATS-type prenyltransferases at the family level, but it also enables future efforts aimed at identifying new candidates for biocatalytic transformations of aromatic compounds.

microbiology↗

bioRxiv2023

Visualisation of gene expression within the context of tissues: an X-ray computed tomography-based multimodal approach

The development of an organism is orchestrated by the spatial and temporal expression of genes. Accurate visualisation of gene expression patterns in the context of the surrounding tissues offers a glimpse into the mechanisms that drive morphogenesis. We developed correlative light-sheet fluorescence microscopy and X-ray computed tomography approach to map gene expression patterns to the whole organisms 3D anatomy at cellular resolution. We show that this multimodal approach is applicable to gene expression visualised by protein-specific antibodies and fluorescence RNA in situ hybridisation, offering a detailed understanding of individual phenotypic variations in model organisms. Furthermore, the approach provides a unique possibility to identify tissues together with their 3D cellular and molecular composition in anatomically less-defined in vitro models, such as organoids. We anticipate that the visual and quantitative insights into the 3D distribution of gene expression within tissue architecture, by the multimodal approach developed here, will be equally valuable for reference atlases of model organisms development, as well as for comprehensive screens and morphogenesis studies of in vitro models.

developmental biology↗

bioRxiv2023

Structural characterization and extended substrate scope analysis of two Mg2+-dependent O-methyltransferases from bacteria

Oxygen-directed methylation is a ubiquitous tailoring reaction in natural product pathways catalysed by O-methyltransferases (OMTs). Promiscuous OMT biocatalysts are thus a valuable asset in the toolkit for sustainable synthesis and optimization of known bioactive scaffolds for drug development. Here, we characterized two bacterial OMTs from Desulforomonas acetoxidans and Streptomyces avermitilis in terms of their enzymatic properties and substrate scope and determined their crystal structures. Both OMTs methylated a wide range of catechol-like substrates, including flavonoids, coumarins, hydroxybenzoic acids and their respective aldehydes, an anthraquinone and an indole. One enzyme also accepted a steroid. The product range included pharmaceutically relevant compounds such as (iso)fraxidin, iso(scopoletin), chrysoeriol, alizarin 1-methyl ether and 2-methoxyestradiol. Interestingly, certain non-catechol flavonoids and hydroxybenzoic acids were also methylated. This study expands the knowledge on substrate preference and structural diversity of bacterial catechol OMTs and paves the way for their use in (combinatorial) pathway engineering. Table of contentsTwo promiscuous O-methyltransferases from bacteria were found to methylate a panel of catechol substrates towards high-value medicinal compounds. Surprisingly, the non-catechol substrates 5-hydroxyflavonoids and o-hydroxybenzoic acids/aldehydes were also methylated at low conversion rates. The crystal structures reveal potential target sites for enzyme engineering for biocatalytic applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/526015v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@4d9028org.highwire.dtl.DTLVardef@334ceborg.highwire.dtl.DTLVardef@1ff016forg.highwire.dtl.DTLVardef@b74b8b_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2022

A versatile semiautomated image analysis workflow for time-lapsed camera trap image classification.

O_LICamera trap arrays can generate thousands to millions of images that require exorbitant time and effort to classify and annotate by trained observers. Computer vision has evolved as an automated alternative to manual classification. The most popular computer vision solution is the supervised Machine Learning technique, which uses labeled images to train automated classification algorithms. C_LIO_LIWe propose a multi-step semi-automated workflow that consists of (1) identifying and separating bad-from good-quality images, (2) parsing good images into animals, humans, vehicles, and empty, and (3) cropping animals from images and classifying them into species for manual inspection. We trained, validated, and evaluated this approach using 548,627 images from 46 cameras in two regions of the Arctic (northeastern Norway, and Yamal Peninsula, Russia). C_LIO_LIWe obtained an accuracy of 0.959 for all three steps combined with the complete year test data set at Varanger and 0.922 at Yamal, reducing the number of images that required manual inspection to 7.9% of the original set from Varanger and 3.2% from Yamal. C_LIO_LIResearchers can modify this multi-step process to meet their specific needs for monitoring and surveying wildlife, providing greater flexibility than current options available for image classification. C_LI

ecology↗

bioRxiv2019

No evidence for disruption of global patterns of nest predation in shorebirds

Kubelka et al. (Science, 9 November 2018, p. 680-683) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

ecology↗