Pavel Volynsky1, Roman Efremov2, Ilya Mikhalev1, Kira Dobrochaeva1, Alexander Tuzikov1, Elena Korchagina1, Polina Obukhova1, Evgenia Rapoport1, Nicolai Bovin3. 1. Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation. 2. Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation; Higher School of Economics, Myasnitskaya ul. 20, Moscow, 101000, Russian Federation. Electronic address: r-efremov@yandex.ru. 3. Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation. Electronic address: professorbovin@yandex.ru.
Abstract
BACKGROUND: Human blood contains a big variety of natural antibodies, circulating throughout life at constant concentration. Previously, we have found natural antibodies capable of binding to trisaccharide Galα1-4Galβ1-4Glc (Pk) practically in all humans. Intriguingly, the same trisaccharide is a key fragment of glycosphingolipid globotriaosylceramide (Gb3Cer) - normal component of erythrocyte and endothelial cell membrane, i.e. the antibodies and their cognate antigen coexist without any immunological reaction. AIM: To explain the inertness of human anti-Pk antibodies towards own cells. MATERIALS AND METHODS: We used a combination of immunochemical and molecular dynamics (MD) experiments. Antibodies were isolated using affinity media with Pk trisaccharide, their epitope specificity was characterized using ELISA (enzyme-linked immunosorbent assay) with a set of synthetic glycans related to Pk synthetic glycans and FACS (Fluorescence-Activated Cell Sorting) analysis of cells with inserted natural Gb3Cer and its synthetic analogue. Conformations and clustering of glycolipids immersed into a lipid bilayer were studied using MD simulations. RESULTS: Isolated specific antibodies were completely unable to bind natural Gb3Cer both inserted into cells and in artificial membrane, whereas strong interaction took place with synthetic analogue differing by the presence of a spacer between trisaccharide and lipid part. MD simulations revealed: i) although membrane-bound glycans do not form stable long-living aggregates, their transient packing is more compact in natural Gb3 as compared with the synthetic analog, ii) similar conformation of Pk glycan in composition of the glycolipids, iii) no effect on the mentioned above results when cholesterol was inserted into membrane, and iv) better accessibility of the synthetic version for interaction with proteins. CONCLUSIONS: Both immunochemical and molecular dynamics data argue that the reason of the "tolerance" of natural anti-Pk antibodies towards cell-bound Gb3Cer is the spatial inaccessibility of Pk glycotope for interaction. We can conclude that the antibodies are not related to the blood group P system.
BACKGROUND:Human blood contains a big variety of natural antibodies, circulating throughout life at constant concentration. Previously, we have found natural antibodies capable of binding to trisaccharide Galα1-4Galβ1-4Glc (Pk) practically in all humans. Intriguingly, the same trisaccharide is a key fragment of glycosphingolipid globotriaosylceramide (Gb3Cer) - normal component of erythrocyte and endothelial cell membrane, i.e. the antibodies and their cognate antigen coexist without any immunological reaction. AIM: To explain the inertness of human anti-Pk antibodies towards own cells. MATERIALS AND METHODS: We used a combination of immunochemical and molecular dynamics (MD) experiments. Antibodies were isolated using affinity media with Pk trisaccharide, their epitope specificity was characterized using ELISA (enzyme-linked immunosorbent assay) with a set of synthetic glycans related to Pk synthetic glycans and FACS (Fluorescence-Activated Cell Sorting) analysis of cells with inserted natural Gb3Cer and its synthetic analogue. Conformations and clustering of glycolipids immersed into a lipid bilayer were studied using MD simulations. RESULTS: Isolated specific antibodies were completely unable to bind natural Gb3Cer both inserted into cells and in artificial membrane, whereas strong interaction took place with synthetic analogue differing by the presence of a spacer between trisaccharide and lipid part. MD simulations revealed: i) although membrane-bound glycans do not form stable long-living aggregates, their transient packing is more compact in natural Gb3 as compared with the synthetic analog, ii) similar conformation of Pk glycan in composition of the glycolipids, iii) no effect on the mentioned above results when cholesterol was inserted into membrane, and iv) better accessibility of the synthetic version for interaction with proteins. CONCLUSIONS: Both immunochemical and molecular dynamics data argue that the reason of the "tolerance" of natural anti-Pk antibodies towards cell-bound Gb3Cer is the spatial inaccessibility of Pk glycotope for interaction. We can conclude that the antibodies are not related to the blood group P system.
Authors: Radoslaw Kaczmarek; Katarzyna Szymczak-Kulus; Anna Bereźnicka; Krzysztof Mikołajczyk; Maria Duk; Edyta Majorczyk; Anna Krop-Watorek; Elżbieta Klausa; Joanna Skowrońska; Bogumiła Michalewska; Ewa Brojer; Marcin Czerwinski Journal: PLoS One Date: 2018-04-30 Impact factor: 3.240
Authors: Anton Zalygin; Daria Solovyeva; Ivan Vaskan; Stephen Henry; Marcel Schaefer; Pavel Volynsky; Alexander Tuzikov; Elena Korchagina; Ivan Ryzhov; Alexey Nizovtsev; Konstantin Mochalov; Roman Efremov; Eleonora Shtykova; Vladimir Oleinikov; Nicolai Bovin Journal: ChemistryOpen Date: 2020-04-06 Impact factor: 2.911