Abstract OR-2: The Formation of Dps-DNA Complexes under Different Conditions According to Cryo-EM and SAXS

Background: The effect of Dps-DNA co-crystals formation, which occurs in stressed Escherichia coli cells exposed to extreme conditions, is well described the literature. However, exact mechanisms formation are yet be postulated remaining largely unknown. Here we summarize results obtained by our group over last few years using cryo-Electron Microscopy (cryo-EM) and Small Angle X-ray Scattering (SAXS). Methods: Samples for cryo-EM were plunge frozen liquid ethane with Vitrobot Mark IV studied Titan Krios (ThermoFisher Scientific, US) cryo-EM, equipped Falcon 2 direct electron detector, Image corrector (CEOS, Germany), Volta phase plate. Single Particle Analysis (SPA) Tomography (cryo-ET) studies conducted 300 kV accelerating voltage low dose mode EPU software US). Cryo-EM data processing was Warp, CryoSPARC, IMOD, EMAN, Relion packages. SAXS measurements performed at EMBL on P12 BioSAXS beam line PETRAIII storage ring (DESY, Hamburg). Results: In this work, complex thoroughly complementary (including SPA, cryo-ET, subtomogram averaging) methods. individual complexes Dps small linear DNA fragments Dps-Dps interaction visualized cryo-EM. It found that remains stable under various conditions while addition different ions leads disruption co-crystals, process completely or partially reversible. Conclusion: Recent showed adopt triclinic cubic crystal lattice (FEBS Lett., 2019; Biomolecules, 2020). present fragments, demonstrate effects MgCl2, FeSO4, EDTA protein structure, discuss influence temperature time co-crystals.