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Vol 52(2018) N 6 p. 913-921; DOI 10.1134/S0026893318060109 Full Text

A.L. Ksenofontov1*, E.N. Dobrov1, N.V. Fedorova1, A.M. Arutyunyan1, A.E. Golanikov2, L. Järvekülg3, E.V. Shtykova2,4

Structure of Potato Virus A Coat Protein Particles and Their Dissociation

1Belozersky Institute of' Physico-Chemical Biology, Moscow State University, Moscow, 119991 Russia
2Shubnikov Institute of Crystallography, Crystallography and Photonics Federal Scientific Research Centre, Russian Academy of Sciences, Moscow, 119333 Russia
3Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618 Estonia
4Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 119991 Russia

*ksenofon@belozersky.msu.ru
Received - 2018-03-06; Accepted - 2018-05-10

This paper reports on a complex structural analysis of the potato virus A coat protein using a set of complementary physico-chemical methods. We have demonstrated previously that this protein does not exist as individual subunits in solution and undergoes association into oligomers with subsequent transition to β-conformation. The purpose of the present work was to study the possible mechanisms of this transformation and to search for methods that dissociate protein oligomers. To analyze the low resolution protein structure in solution, small-angle X-ray scattering was used. Stable particles representing clusters of 30 coat protein subunits were present even in an aqueous salt solution with a high ionic strength and pH (pH 10.5; 0.5 M NaCl). The particles did not dissociate in the presence of 10 mM dextran sulfates (15 and 100 kDa). Dissociation in the presence of 5.2 mM sodium dodecyl sulfate results in the formation of the subunit-detergent complexes consisting of 10-12 small particles joined together like "beads on a string". Similar effects of sodium dodecyl sulfate were shown for serum albumins (bovine and human). Denaturation of the potato virus A coat protein molecules occurs in the presence of detergent concentrations that are seven times lower than that in albumins (5.2 and 35 mM), which confirms low stability of the potato virus A coat protein. Using spectral methods, preservation of the secondary structure and loss of the tertiary structure of the protein in its complex with sodium dodecyl sulfate have been demonstrated. Possible mechanism for protein particle formation through the interaction between unordered terminal domains and their transformation into β-structures has been suggested.

potyviruses, coat protein, potato virus A, virus-like particles, physico-chemical methods, small-angle X-ray scattering, dextran sulfate, sodium dodecyl sulfate, disordered and β-structures



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