STUDY ON THE AMYLOIDOIGENIC POTENTIAL OF NON-SPECIFIC YERSINIA PSEUDOTUBERCULOSIS PORINS

The paper considers the process of formation and properties of amyloid-like aggregates of outer membrane non-specific porins (OmpC and OmpF) of the gram-negative bacterium Yersinia pseudotuberculos in an acidic medium (pH 4.5) at elevated temperature. The dynamics of the formation of amyloid-like aggregates of porins was monitored after two and four weeks of incubation (at 42 °C) and after 3-5 hours (at 90 °C) by staining the samples with amyloid-specific dye thioflavin T, analyzing the spectra of circular dichroism in the far UV region, IR -spectroscopy and confocal microscopy. It was found that in the case of porin OmpC, incubation under mild conditions (42°C) leads to a reversible accumulation of α-helical regions in the protein polypeptide chain. No significant changes are observed in the spatial structure of OmpF porin under these conditions, however, under harsh conditions (95 ºC) amyloid-like aggregates are formed, which are characterized by an increased content of the β-sheet structure. Using IR spectroscopy, it was shown that the conformational rearrangement in the molecule of OmpF porin is associated with a change in the quantity and quality of elements of the β-structure. According to confocal microscopy, the aggregates of the studied non-specific porins can be considered as intermediate products of the amyloidogenic pathway - oligomers. According to the literature data, these oligomers, which precede the formation of mature fibrils, have membranolytic and cytotoxic properties. For heated samples of the studied porins during reconstitution into bilayer lipid membranes, neither pore-forming nor membranolytic activity was detected. With respect to Neuro-2a CCL-131™ mouse neuroblastoma cells, the aggregates of OmpF and OmpC porins obtained after incubation had a higher toxicity compared to the initial protein samples.