Presentations

Structural organization of DNA in bacteria. Various types of stress

Krupyanskii Y.F., Kovalenko V.V., Loiko N.G., Tereshkin E.V., Generalova A.A., Tereshkina K.B., Sokolova O.S.¹, Peters G.S.²

N. N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Russia, 119991, Moscow, Kosygina St. 4, +7 (495) 939 73 00, E-mails: yuriifkru@gmail.com , yufk@chph.ras.ru

¹Moscow State University, Moscow, M. V. Lomonosov Moscow State University, Faculty of Biology, Moscow, Russia

²National Research Center Kurchatov Institute, KISI-Kurchatov, Moscow, Russia

Bacterial genomic DNA interacts with nucleoid-associated proteins and is found in a highly condensed and functional form in the cell's nucleoid. In actively growing cells, DNA is organized hierarchically with three levels of DNA compaction [1]. This organization, or very high level of dynamic order, is critically dependent on energy consumption and cannot be maintained in starved bacteria. DNA architecture in dormant cells was studied using synchrotron radiation diffraction and transmission electron microscopy (TEM) [1]. Intracellular nanocrystalline, liquid crystalline, and folded nucleosome-like DNA structures were detected [1]. Changes in DNA architecture under the stressful influence of a chemical analogue of the autoinducer of anabiosis (4-hexylresorcinol, 4HR) were further studied [2]. Increasing the concentration of 4HR causes cells to enter an anabiotic dormant state. Studies of DNA architecture in the anabiotic state indicate that the DNA structure is identical in the anabiotic state and in the dormant state under starvation stress [2]. Condensed DNA structures were further studied in bacteria exposed to the antibiotic ciprofloxacin (CIP). The diffraction structure of the spectra after exposure to CIP resembles the structure of the spectra for DNA in a cell in a state of anabiotic dormancy. A special experiment was conducted using a mutant Dps strain (K-12 Δdps, a strain lacking Dps proteins). The K-12 Δdps experiment allows for a critical analysis of DNA packaging models under various types of stress.

1. Krupyanskii Y.F. Determination of DNA architecture of bacteria under various types of stress, methodological approaches, problems, and solutions. Biophysical Reviews, 2023, https://doi.org/10.1007/s12551-023-01122-0

2. Krupyanskii Yu. F. et al. The Structure of DNA in Anabiotic and Mummified Escherichia coli Cells. Russian Journal of Physical Chemistry B, 2024, Vol. 18, No. 4, pp. 1134–1140.

https://doi.org/10.1134/S1990793124700441

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