Biology subjects

Vishnyakov, I. E.

Publications and source records attributed to Vishnyakov, I. E..

3 recordsLinked to original sources

bioRxiv2025

Mycoplasma gallisepticum FtsZ demonstrates properties that distinguish it from other known homologs

In bacteria, cell division usually occurs through binary fission, with the participation of genes from the dcw cluster. In mollicutes, this cluster is significantly reduced -- often only the ftsZ, ftsA, mraZ, and mraW genes remain, and sometimes ftsZ is completely absent. FtsZ is a key division protein that forms the Z-ring, but its role in mollicutes is questionable due to the absence of many cell division proteins and the cell wall. In the current study, we investigated the FtsZ protein of Mycoplasma gallisepticum, a bacterium with a reduced set of putative cell division genes (ftsZ, ftsA, ftsK). The results show that, unlike in well-studied bacteria, FtsZ in M. gallisepticum often exhibits polar rather than mid-cell localization. Overexpression of fluorescently labeled FtsZ enhances this polar localization and may lead to minicell formation. The FtsZ concentration was measured and, together with in vitro data, confirmed its ability to polymerize, similar to its homologs. Protein-protein interactions were also analyzed and confirmed the link of FtsZ to cell division. Overall, the results support the role of FtsZ in cell division, though its properties differ significantly from other known homologs.

molecular biology↗

bioRxiv2024

Genomic Transfer via Membrane Vesicle: A Strategy of Giant Phage phiKZ for Early Infection

During infection, the giant phiKZ phage forms a specialized structure at the center of the host cell called the phage nucleus. This structure is crucial for safeguarding viral DNA against bacterial nucleases and for segregating the transcriptional activities of late genes. Here, we describe a morphological entity, the early phage infection vesicle (EPI vesicle), which appears to be responsible for earlier gene segregation at the beginning of the infection process. Using cryo-electron microscopy, electron tomography, and fluorescence microscopy with membrane-specific dyes, we found that the EPI vesicle is enclosed in a lipid bilayer originating, apparently, from the inner membrane of the bacterial cell. Our investigations further disclose that the phiKZ EPI vesicle contains both viral DNA and viral RNA polymerase (vRNAP). We have observed that the EPI vesicle migrates from the cell pole to the center, displaying co-localization with ChmA, the primary protein of the phage nucleus. While phage DNA is transported into the phage nucleus after phage maturation, the EPI vesicle remains outside. We hypothesized that the EPI vesicle acts as a membrane transport agent, efficiently delivering phage DNA to the phage nucleus while protecting it from the nucleases of the bacterium.

molecular biology↗

bioRxiv2023

The Dynamics of Synthesis and Localization of Jumbo Phage RNA Polymerases inside Infected Cells

A nucleus-like structure composed of phage-encoded proteins and containing replicating viral DNA is formed in Pseudomonas aeruginosa cells infected by jumbo bacteriophage phiKZ. The PhiKZ genes are transcribed independently from host RNA polymerase (RNAP) by two RNAPs encoded by the phage. The virion RNAP (vRNAP) transcribes early viral genes and must be injected into the cell with phage DNA. The non-virion RNAP (nvRNAP) is composed of early genes products and transcribes late viral genes. In this work, the dynamics of phage RNAPs localization during phage phiKZ infection was studied. We provide direct evidence of PhiKZ vRNAP injection in infected cells and show that it is excluded from the phage nucleus. The nvRNAP is synthesized shortly after the onset of infection and localizes in the nucleus. We propose that spatial separation of two phage RNAPs allows coordinated expression of phage genes belonging to different temporal classes.

molecular biology↗