Amphipathic CRAC-Containing Peptides Derived from the Influenza Virus A M1 Protein Modulate Cholesterol-Dependent Activity of Cultured IC-21 Macrophages

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A. Ya. Dunina-Barkovskaya^1,a*, Kh. S. Vishnyakova², A. O. Golovko³, A. M. Arutyunyan¹, L. A. Baratova¹, O. V. Bathishchev⁴, and V. A. Radyukhin^1,b*

¹Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia

²Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia

³Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia

⁴Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia

^* To whom correspondence should be addressed.

Received January 11, 2018; Revision received May 14, 2018

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Entry of many viral and bacterial pathogens into host cells depends on cholesterol and/or cholesterol-enriched domains (lipid rafts) in the cell membrane. Earlier, we showed that influenza virus A matrix protein M1 contains amphipathic α-helices with exposed cholesterol-recognizing amino acid consensus (CRAC) motifs. In order to test possible functional activity of these motifs, we studied the effects of three synthetic peptides corresponding to the CRAC-containing α-helices of the viral M1 protein on the phagocytic activity of cultured mouse IC-21 macrophages. The following peptides were used: LEVLMEWLKTR (M1 α-helix 3, a.a. 39-49; further referred to as peptide 1), NNMDKAVKLYRKLK (M1 α-helix 6, a.a. 91-105; peptide 2), and GLKNDLLENLQAYQKR (M1 α-helix 13, a.a. 228-243; peptide 3). We found that all three peptides modulated interactions of IC-21 macrophages with non-opsonized 2-µm target particles. The greatest effect was demonstrated by peptide 2: in the presence of 35 μM peptide 2, the phagocytic index of IC-21 macrophages exceeded the control value by 60%; 10-11 mM methyl-β-cyclodextrin abolished this effect. Peptides 1 and 3 exerted weak inhibitory effect in a narrow concentration range of 5-10 μM. The dose-response curves could be approximated by a sum of two (stimulatory and inhibitory) components with different Hill coefficients, suggesting existence of at least two peptide-binding sites with different affinities on the cell surface. CD spectroscopy confirmed that the peptides exhibit structural flexibility in solutions. Altogether, our data indicate that amphipathic CRAC-containing peptides derived from the viral M1 protein modulate lipid raft-dependent processes in IC-21 macrophages.

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KEY WORDS: peptides, influenza virus protein M1, amphipathic helices, lipid rafts, cholesterol, macrophages, phagocytosis

DOI: 10.1134/S0006297918080096

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