Biology subjects

Moiseenko, A. V.

Publications and source records attributed to Moiseenko, A. V..

3 recordsLinked to original sources

bioRxiv2026

Structural features of E. coli Stx bacteriophage phi24B revealed with cryo-electron microscopy

Shiga toxin-converting bacteriophages play a critical role in the emergence and virulence of pathogenic Escherichia coli strains. Despite their significance, detailed structural information on these phages remains scarce. Here we present a high-resolution cryo-electron microscopy and proteomic analysis of the phi24B bacteriophage, revealing an icosahedral capsid with T=9 symmetry, decorated by a processed esterase protein (gp84) and stabilized by cementing proteins. The tail assembly comprises a dodecameric portal, two rings of adapter proteins sharing a common fold, a hexameric nozzle, six lateral tail fibers, and a flexible central needle fiber. The binding sites of the fibers are described. Comparative analysis indicates conservation of the tail structure with related podoviruses but very different peripheral features.

biophysics↗

bioRxiv2025

Target-induced Argonaute-HNH filaments confer bacterial immunity

Argonaute proteins provide innate immunity in all domains of life through guide-dependent recognition of invader nucleic acids. While eukaryotic Argonautes (eAgos) act on RNA during RNA interference, prokaryotic Argonautes (pAgos) mainly recognize DNA targets. Many eAgos and some pAgos are active nucleases that directly cleave their targets. In contrast, short pAgos lack the nuclease activity and are co-encoded with additional effectors. Diverse effector domains in short pAgo systems include NADases and tentative nucleases, but their mechanisms of activation remain largely unknown. Here, we characterize SPARHA systems (short prokaryotic argonautes, HNH-associated) encoding HNH nuclease effectors. We show that short pAgo activates the HNH effector after RNA-guided DNA recognition. Target recognition induces formation of filaments of SPARHA with double active sites formed at the interfaces of repetitive HNH domains, which results in indiscriminate collateral degradation of DNA and protects bacterial population from invaders. The results show that pAgos and associated effectors act as modular two-component systems that translate recognition of specific DNA into immune response through assembly of supramolecular complexes, deleterious for invaders and potentially useful for biotechnology.

molecular biology↗

bioRxiv2024

New viruses infecting hyperthermophilic bacterium Thermus thermophilus

Highly diverse phages infecting thermophilic bacteria of the Thermus genus have been isolated over the years from hot springs around the world. Many of these phages are unique, rely on highly unusual developmental strategies, and encode novel enzymes. The variety of Thermus phages is clearly undersampled, as evidenced, for example, by a paucity of phage-matching spacers in Thermus CRISPR arrays. Using water samples collected from hot springs in the Kunashir Island from the Kuril archipelago and from the Tsaishi and Nokalakevi districts in the Republic of Georgia we isolated several distinct phages infecting laboratory strains of Thermus thermophilus. Genomic sequence analysis of 11 phages revealed both close relatives of previously described Thermus phages isolated from geographically distant sites, as well as phages with very limited similarity to earlier isolates. Comparative analysis allowed us to predict several accessory phage genes whose products may be involved in host defense/interviral warfare, including a putative Type V CRISPR-cas system.

microbiology↗