Chaperone and Immunoglobulin-Binding Activities of Skp Protein from Yersinia pseudotuberculosis

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E. V. Sidorin^1,a*, V. A. Khomenko¹, N. Yu. Kim¹, and T. F. Solov’eva¹

¹Elyakov Pacific Institute of Bioorganic Chemistry, Far-Eastern Branch of the Russian Academy of Sciences, 690022 Vladivostok, Russia

^* To whom correspondence should be addressed.

Received May 20, 2019; Revised August 20, 2019; Accepted September 10, 2019

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Here, we determined qualitative and quantitative characteristics of the chaperone and immunoglobulin-binding activities of recombinant Skp protein (rSkp) from Yersinia pseudotuberculosis using the methods of dynamic light scattering and surface plasmon resonance. Commercial human polyclonal IgG and Fc and Fab fragments of human IgG were used as substrate proteins. The activity of rSkp strongly depended on the medium pH. The most stable low-molecular-weight complexes with a hydrodynamic radius up to 10 nm were formed by rSkp and protein substrates at acidic pH values. Under these conditions, rSkp exhibited the lowest propensity to self-association and the highest affinity for human IgG and its Fc and Fab fragments, as well as prevented their aggregation most efficiently (i.e., demonstrated the maximal chaperone activity). As the medium pH increased, the affinity of rSkp for IgG and its fragments decreased; rSkp was not able to completely prevent the aggregation of protein substrates, but significantly slowed it down. The obtained information may be of practical interest, since the stability of therapeutic IgG preparations affects their safety and efficacy in medical applications.

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KEY WORDS: Skp chaperone, Yersinia pseudotuberculosis, human immunoglobulin G, Fc and Fab fragments of IgG, protein–protein interactions, dynamic light scattering, surface plasmon resonance

DOI: 10.1134/S0006297920010071

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