Interaction of Cholera Toxin B-subunit with Human T-lymphocytes

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E. V. Navolotskaya^1*, V. B. Sadovnikov¹, D. V. Zinchenko¹, Y. A. Zolotarev², V. M. Lipkin³, and V. P. Zav’yalov⁴

¹Branch of Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; E-mail: navolotskaya@fibkh.serpukhov.su, elenanavolots@gmail.com

²Institute of Molecular Genetics, Russian Academy of Sciences, 123182 Moscow, Russia

³Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia

⁴University of Turku, Turku, 20500, Finland

^* To whom correspondence should be addressed.

Received May 4, 2017; Revision received June 2, 2017

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In this work, ¹²⁵I-labeled cholera toxin B-subunit (CT-B) (specific activity 98 Ci/mmol) was prepared, and its high-affinity binding to human blood T-lymphocytes (K_d = 3.3 nM) was determined. The binding of the ¹²⁵I-labeled CT-B was inhibited by unlabeled interferon-α₂ (IFN-α₂), thymosin-α₁ (TM-α₁), and by the synthetic peptide LKEKK, which corresponds to sequences 16-20 of human TM-α₁ and 131-135 of IFN-α₂ (K_i 0.8, 1.2, and 1.6 nM, respectively), but was not inhibited by the unlabeled synthetic peptide KKEKL with inverted sequence (K_i > 1 µM). In the concentration range of 10-1000 nM, both CT-B and peptide LKEKK dose-dependently increased the activity of soluble guanylate cyclase (sGC) but did not affect the activity of membrane-bound guanylate cyclase. The KKEKL peptide tested in parallel did not affect sGC activity. Thus, the CT-B and peptide LKEKK binding to a common receptor on the surface of T-lymphocytes leads to an increase in sGC activity.

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KEY WORDS: peptides, receptors, thymosin-α₁, interferon-α, T-lymphocytes

DOI: 10.1134/S0006297917090061

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