Biology subjects

Tereshkina, K.

Publications and source records attributed to Tereshkina, K..

3 recordsLinked to original sources

bioRxiv2026

THE ROLE OF LIQUID CRYSTAL ORDERING IN THE STRUCTURAL ORGANIZATION OF DNA IN BACTERIA.

This paper presents and critically reviews the results of original and some literature based experimental studies conducted by the authors last years on the structural organization of DNA in dormant (starvation stress), anabiotic dormant (4 HR treatment) E. coli cells, as well as the K12 {Delta}dps strain, which lacks the Dps protein (Dps null E. coli). The experimental data includes small-angle synchrotron radiation diffraction (SAXS) and transmission electron microscopy (TEM) data. Synchrotron radiation diffraction experiments on K12{Delta}dps cells allowed us to conclude that peaks at 44.3, 22.1, and 14.8 angstrom resolutions are associated exclusively with ordered DNA organization. Peaks at 44.3, 22.1, and 14.8 angstrom resolutions are also observed for samples of dormant (starvation stress) cells and anabiotically dormant cells. Therefore, this ordered DNA organization also applies to samples of dormant and anabiotically dormant cells. A model is proposed that considers the ordered DNA organization in the cell as a cholesteric liquid crystal. The powder diffraction pattern calculated based on this model is compared with experimental small angle X ray scattering (SAXS) data obtained on Dps-null cell samples. The model completely reproduces the key features of the experimental diffraction pattern from Dps-null cell samples. Accordingly, the cholesteric liquid crystal model corresponds to DNA packaging in dormant and anabiotically dormant cells. Cholesteric liquid crystal ordering should be further considered in all models of cellular DNA packaging. To address the question of which structural organization of DNA predominates in the cell: the cholesteric liquid crystal or nanocrystalline or whether they coexist and fully manifest themselves under different external conditions, it is necessary to utilize the latest methodological advances in structural analysis.

biophysics↗

bioRxiv2023

THE STRUCTURE OF DNA IN ANABIOTIC AND MUMMIFIED CELLS

Investigations of structural organization of DNA for stressed (increased stress resistance), anabiotic and mummified cells obtained by introducing 4-hexylresorcinol at different concentrations for different stages of cell culture growth using diffraction of synchrotron radiation were done. Experimental studies allow us to conclude that 4-hexylresorcinol is the initiator of the cell transition to the anabiotic and mummified states at stationary state. At pre-stationary state of growth 4-hexylresorcinol initiates a transition of cells to a mummified state but not to anabiotic one. The structure of DNA within a cell in the anabiotic dormant state (practically complete absence of metabolism) and the dormant state (starvation stress) coincide (forms nanocrystalline structures). Our data suggest the universality of DNA condensation or the universality of DNA protection by a protein Dps for dormant state, regardless of the type of stress. Mummified state (the complete absence of metabolism) is very different in structure (has no ordering within a cell).

cell biology↗

bioRxiv2020

Morphological peculiarities of DNA-protein complexes in dormant Escherichia coli cells, subjected to prolonged starvation

One of the adaptive strategies for the constantly changing conditions of the environment utilized in bacterial cells involves the condensation of DNA in complex with the DNA-binding protein, Dps. With the use of electron microscopy and electron tomography, we observed several morphologically different types of DNA condensation in dormant Escherichia coli cells, namely: nanocrystalline, liquid crystalline, and the folded nucleosome-like. We confirmed the presence of both Dps and DNA in all of the ordered structures using EDX analysis. The comparison of EDX spectra obtained for the three different ordered structures revealed that in nanocrystalline formation the majority of Dps protein is tightly bound to nucleoid DNA. We demonstrated that the population of the dormant cell is structurally heterogeneous, which allows cells to respond flexibly to environmental changes. It increases the ability of the whole bacterial population to survive under extreme stress conditions.

cell biology↗