Biology subjects

Stach, J. E. M.

Publications and source records attributed to Stach, J. E. M..

4 recordsLinked to original sources

bioRxiv2024

Delineation of the Complete Reaction Cycle of a Natural Diels-Alderase

The Diels-Alder reaction is one of the most effective methods for the synthesis of substituted cyclohexenes. The development of protein catalysts for this reaction remains a major priority, affording new sustainable routes to high value target molecules. Whilst a small number of natural enzymes have been shown capable of catalysing [4+2] cycloadditions, there is a need for significant mechanistic understanding of how these prospective Diels-Alderases promote catalysis to underpin their development as biocatalysts for use in synthesis. Here we present a molecular description of the complete reaction cycle of the bona fide natural Diels-Alderase AbyU, which catalyses formation of the spirotetronate skeleton of the antibiotic abyssomicin C. This description is derived from X-ray crystallographic studies of AbyU in complex with a non-transformable synthetic substrate analogue, together with transient kinetic analyses of the AbyU catalysed reaction and computational reaction simulations. These studies reveal the mechanistic intricacies of this enzyme system and establish a foundation for the informed reengineering of AbyU and related biocatalysts.

biochemistry↗

bioRxiv2024

Diversity and structure of the deep-sea sponge microbiome in the equatorial Atlantic Ocean

Sponges (phylum Porifera) harbour specific microbial communities that drive the ecology and evolution of the host. Understanding the structure and dynamics of these communities is emerging as a primary focus in marine microbial ecology research. Much of the work to date has focused on sponges from warm and shallow coastal waters, while sponges from the deep ocean remain less well-studied. Here, we present a metataxonomic analysis of the microbial consortia associated with 23 deep-sea sponges. We identify a high abundance of archaea relative to bacteria across these communities, with certain sponge microbiomes comprising more than 90% archaea. Specifically, the archaeal family Nitrosopumilaceae are prolific, comprising over 99% of all archaeal reads. Our analysis revealed sponge microbial communities mirror the host sponge phylogeny, indicating a key role for host taxonomy in defining microbiome composition. Our work confirms the contribution of both evolutionary and environmental processes to the composition of microbial communities in deep-sea sponges. ImportanceThe deep ocean is the largest biome on Earth, accounting for >90% of the planets marine environment. Despite this it remains a largely unexplored ecosystem, with less than 0.01% of the deep seafloor having been quantitatively sampled. Deep-sea sponges are ancient metazoans which harbour complex microbial communities and much still remains to be learned about the composition and diversity of these unique microbiomes. In an effort to address this, here we report a metataxonomic analysis of the microbial consortia associated with 23 deep-sea sponges from the equatorial Atlantic Ocean. Our findings reveal intricate, species-specific microbial communities dominated by ammonia-oxidizing archaea. This study highlights the significant role sponges play in shaping microbial consortia, providing new insights into deep-sea ecosystem dynamics. Importantly, our findings provide a scientific basis for understanding the evolutionary relationships between sponges and their symbiotic microorganisms.

microbiology↗

bioRxiv2022

Discovery and biosynthetic assessment of Streptomyces ortus sp nov. isolated from a deep-sea sponge

The deep sea is known to host novel bacteria with the potential to produce a diverse array of undiscovered natural products. Understanding these bacteria is thus of broad interest in ecology and could also underpin applied drug discovery, specifically in the area of antimicrobials. Here, we isolate a new strain of Streptomyces from the tissue of the deep-sea sponge Polymastia corticata collected at a depth of 1869 m from the Gramberg seamount in the Atlantic Ocean. This strain, which was given the initial designation A15ISP2-DRY2T, has a genome size of 9.29 Mb with a GC content of 70.83%. Phylogenomics determined that A15ISP2-DRY2T represents a novel species within the genus Streptomyces as part of the Streptomyces aurantiacus clade. The biosynthetic potential of A15ISP2-DRY2T was assessed relative to other members of the aurantiacus clade via comparative gene cluster family (GCF) analysis. This revealed a clear congruent relationship between phylogeny and GCF content. A15ISP2-DRY2T contains six unique GCFs absent elsewhere in the clade. Culture-based assays were used to demonstrate the antibacterial activity of A15ISP2-DRY2T against two drug-resistant human pathogens. We thus determine A15ISP2-DRY2T to be a novel bacterial species with considerable biosynthetic potential and propose the systematic name Streptomyces ortus sp. nov. Impact StatementThe Streptomyces genus has contributed more to our antibiotic arsenal than any other group of bacteria or fungi. Despite decades of exploration, global analysis has suggested they still possess more undiscovered biosynthetic diversity than any other bacterial group. Isolating novel species of Streptomyces is therefore a priority for antibiotic discovery. Here we isolate a novel strain from a deep-sea sponge and use comparative cluster analysis to identify six biosynthetic clusters unique to our deep-sea strain. This work demonstrates the utility of continuing to isolate novel Streptomyces strains for antibiotic discovery and, for the first time, we used species tree-gene cluster tree reconciliation to assess the contribution of vertical evolution on the biosynthetic gene cluster content of Streptomyces.

genomics↗

bioRxiv2019

Out of the abyss: Genome and metagenome mining reveals unexpected environmental distribution of abyssomicins

Natural products have traditionally been discovered through the screening of culturable microbial isolates from all sort of environments. The sequencing revolution allowed the identification of dozens of biosynthetic gene clusters (BGCs) within single bacterial genomes, either from cultured or uncultured strains. However, we are still far from fully exploiting the microbial reservoir, as most of the species are non-model organisms with complex regulatory systems and yet recalcitrant to be engineered. Today, genomic and metagenomic data produced by laboratories worldwide covering the most different natural and artificial environments on Earth, are an invaluable source of raw information from which natural product biosynthesis can be accessed. In the present work, we describe the environmental distribution and evolution of the abyssomicin BGC through the analysis of publicly available genomic and metagenomic data. Our results demonstrate that the selection of a pathway-specific enzyme to direct the genome mining is an excellent strategy that led to the identification of 74 new Diels-Alderase homologs and unveiled a surprising prevalence of the abyssomicin BGC within terrestrial habitats, mainly soil and plant-associated, where we have identified five complete and 12 partial new abyssomicin BGCs and 23 new potential abyssomicin BGCs. Our results strongly support the potential of genome and metagenome mining as a key preliminary tool to inform bioprospecting strategies aiming at the identification of new bioactive compounds such as -but not restricted to-abyssomicins.

microbiology↗