Porins from marine bacteria of the genus Pseudoalteromonas (Gammaproteobacteria: Pseudoalteromonadaceae)
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Outer membrane (OM) fractions were isolated from marine bacteria of the genus Pseudoalteromonas (P. haloplanktis, P. tetraodonis, and Pseudoalteromonas sp. KMM 223). The purity of OM fractions was confirmed by ultracentrifugation in a sucrose gradient. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and the bilayer lipid membrane (BLM) technique, heat-modifiable porin-like proteins were identified among the OM proteins of marine pseudomonads. The pore-forming P-1 and P-2 proteins with molecular masses of 43 and 39 kDa, respectively, were obtained from the marine bacterium P. haloplanktis. The nature of current fluctuations in the BLM and the conductivity of pores formed by these proteins suggest that these isolated porins are not identical in their functional properties. A nonlinear dependence of channel conductivity on salt concentration in the aqueous phase was found for the P-2 protein, which is typical of marine bacterial porins.
Keywordsmarine bacteria outer membrane porins bilayer lipid membrane
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