Interaction of Porin from Yersinia pseudotuberculosis with Different Structural Forms of Endogenous Lipopolysaccharide |
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Authors: | T I Vakorina O D Novikova I N Krasikova G N Naberezhnykh T F Solov'eva Yu S Ovodov |
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Institution: | (1) Far East Branch of the Russian Academy of Sciences, pr. 100-letiya Vladivostoka 159, Pacific Institute of Bioorganic Chemistry, Vladivostok, 690022, Russia;(2) Urals Branch of the Russian Academy of Sciences, ul. Pervomaiskaya 50, Institute of Physiology, Komi Science Center, Syktyvkar, 167982, Russia |
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Abstract: | The interaction of Yersinia pseudotuberculosis porin solubilized in deoxycholate with the S- and R-forms of endogenous lipopolysaccharide (LPS) was studied by the quenching of intrinsic protein fluorescence. The samples of S-LPS differed both in the length of O-specific polysaccharide (n = 1 and 4) and in the acylation degree of the 3-hydroxytetradecanoic acid residues of the lipid A moiety (12-66%). R-LPS (12%) binding to porin was found to occur with positive cooperativity on two integrated structural regions of the R-LPS macromolecule, namely, core oligosaccharide and lipid A. The mode of porin interaction with low-acylated S-LPSs (15 or 20%) coincided with a model involving three types of binding sites. The shape of Scatchard curves of binding indicates that a complex formation between porin and low-acylated S-LPS is cooperative at low and moderate ligand concentration, whereas at near-saturating LPS concentrations porin binds to LPS independently on two types of binding sites. The O-specific polysaccharide chain in the S-LPS macromolecule increases the affinity of its interaction with porin in comparison with R-LPS–porin binding. A significant increase (to 66%) in the degree of S-LPS acylation substantially changed its porin-binding character: the process becomes anti-cooperative with lowered affinity. Thus, the features of LPS–porin interaction significantly depend on the conformational changes in the LPS molecule due to expanding of its hydrophobic region. |
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Keywords: | Yersinia pseudotuberculosis outer membrane lipopolysaccharide porin lipopolysaccharide– protein interaction protein fluorescence |
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