A Novel OmpY Porin FromYersinia Pseudotuberculosis: Structure, Channel-Forming Activity and Trimer Thermal Stability

Abstract

A novel OmpY porin was predicted based on the Yersinia pseudotuberculosis genome analysis. Whereas it has the different genomic annotation such as "outer membrane protein N" (ABS46310.1) in str. IP 31758 or "outer membrane protein C2, porin" (YP_070481.1) in str. IP32953, it might be warranted to rename the OmpN/OmpC2 to OmpY, "outer membrane protein Y", where letter "Y" pertained to Yersinia. Both phylogenetic analysis and genomic localization clearly support that the OmpY porin belongs to a new group of general bacterial porins. The recombinant OmpY protein with its signal sequence was overexpressed in porin-deficient Escherichia coli strain. The mature rOmpY was shown to insert into outer membrane as a trimer. The OmpY porin, isolated from the outer membrane, was studied employing spectroscopic, electrophoretic and bilayer lipid membranes techniques. The far UV CD spectrum of rOmpY was essentially identical to that of Y. pseudotuberculosis OmpF. The near UV CD spectrum of rOmpY was weaker and smoother than that of OmpF. The rOmpY single-channel conductance was 180 ± 20 pS in 0.1 M NaCl and was lower than that of the OmpF porin. As was shown by electrophoretic and bilayer lipid membrane experiments, the rOmpY trimers were less thermostable than the OmpF trimers. The porins differed in the trimer-monomer transition temperature by about 20°C. The three-dimensional structural models of the Y. pseudotuberculosis OmpY and OmpF trimers were generated and the intra- and intermonomeric interactions stabilizing the porins were investigated. The difference in the thermal stability of OmpY and OmpF trimers was established to correlate with the difference in intermonomeric polar contacts.

Thermomechanical Response of a Representative Porin for Biomimetics

“…Thus, the energy required to breakdown the secondary and quaternary structure of bacterial porins is significantly higher than that necessary to unfold BSA and LYS. Also, yet porin aggregates are stable, a variety of transitions associated to changes in their size (i.e., to dimers, trimers, or bigger aggregates) has been detected at temperatures significantly lower than their unfolding temperatures but comparable to the typical unfolding temperatures of conventional proteins, 46−48 which is in agreement with the opposite behaviors of Omp2a and BSA.…”

Adaptive responses of outer membrane porin balance of Yersinia ruckeri under different incubation temperature, osmolarity, and oxygen availability

“…OmpY was recovered as a recombinant protein but we failed in isolating the native protein (Solo'veva et al. ). We found that the gene encoding this porin is also presents in Y. ruckeri genome.…”

“…Previously, we have described a new OmpY porin in Y. pseudotuberculosis initially predicted from the genomic data. OmpY was recovered as a recombinant protein but we failed in isolating the native protein (Solo'veva et al 2011). We found that the gene encoding this porin is also presents in Y. ruckeri genome.…”

“…Potentially, some of them contribute to the bacterial adaptation to balance the expression levels of the major OMPs. Previously, we characterized new minor porin, named OmpY, from Y. pseudotuberculosis (Solo'veva et al 2011). The protein demonstrates features of classical nonspecific porins similar to OmpF and OmpC.…”

“…Previously, we characterized new minor porin, named OmpY, from Y. pseudotuberculosis (Solo'veva et al. ). The protein demonstrates features of classical nonspecific porins similar to OmpF and OmpC.…”