The encoding sequence of the pore-forming OmpF-like protein from the Yersinia pseudotuberculosis outer membrane was cloned and expressed in Escherichia coli cells. Conditions were selected for isolation and refolding of recombinant monomer and porin trimer. Their spatial structures were characterized by the intrinsic protein fluorescence and CD spectroscopy. It was shown that the recombinant porins are similar in the composition of secondary structure elements to the isolated porins, but have a considerably less compact tertiary structure. The pore-forming activities of the recombinant proteins are similar to those of Y. pseudotuberculosis native porins. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.

The pore-forming proteins porins isolated from Yersinia pseudotuberculosis and Y. enterocolitica outer membranes and purified were found, by means of enzyme-linked immunosorbent assays, to be genus-specific antigens. Antiporin antibodies were detected in rabbit antisera to the isolated proteins as well as to total outer membrane proteins and whole bacterial cells. Enzyme-linked immunosorbent and immunoblotting assays demonstrated an antigenic relatedness of porins from five Yersinia species. Key Words: Yersinia porins; antigenic relatedness; enzyme-linked irnmunosorbent assaysThe pore-forming proteins (porins) present in the outer membrane of gram-negative bacteria have pores allowing for transmembrane transfer of hydrophilic substances [8], and some also serve as receptors for bacteriophages [8]. Being among the major surface antigens of bacterial ceils, porins play an important role in the pathogenesis of infection by promoting adhesion of bacteria to (and possibly their invasion into) host cells [3] and affecting the immune response [5,9].Recent years have witnessed mounting interest in the immunochemical and immunobiological properties of outer membranes proteins, including porins, found in gram-negative bacteria. Porins from several members of the family Enterobacteriaceae have been shown to be antigenically related [6,13], and variations in biological activity among surface epitopes of outer membrane proteins have been reported [16]. However, information on the antigenic structures of porins in the genus Yersinia is scarce [2,10].Identification of antigenically related surface components on the outer cell membrane within Enterobacteriaceae genera may provide a basis for the MATERIALS AND METHODS

The dynamics of immune response to pore-forming protein isolated from the outer membrane of Yersinia pseudotuberculosis was studied on CBA and BALB/c mice. Experiments revealed a waveform curves of antibody levels to different porin forms reflecting the successions of immunoglobulin classes and superposition of independent responses to various antigen determinants. The dynamic of immune response to porin depends on the molecular form and dose of the antigen.

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