Biophysical characterization of OprB,a glucose-inducible porin ofPseudomonas aeruginosa |
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| Authors: | John L. Wylie Christine Bernegger-Egli Joe D. J. O'Neil Elizabeth A. Worobec |
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| Affiliation: | (1) Department of Microbiology, University of Manitoba, R3T 2N2 Winnipeg, Manitoba, Canada;(2) Department of Microbiology, University of British Columbia, V6T 1W5 Vancouver, British Columbia, Canada;(3) Department of Chemistry, University of Manitoba, R3T 2N2 Winnipeg, Manitoba, Canada |
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| Abstract: | OprB, a glucose-inducible porin ofP. aeruginosa, was characterized by black lipid bilayer analysis and circular dichroism spectroscopy. Black lipid bilayer analysis of OprB revealed a single-channel conductance of 25 pS, the presence of a glucose binding site with aKs for glucose of 380 ± 40 mM, and the formation of channels with a strong selection for anions. Analysis ofP. aeruginosa OprB circular dichroism spectra revealed a high  sheet content (40%) which is within the range of that determined for other porins. Values obtained from black lipid bilayer analysis were compared to those previously obtained for OprB ofP. putida [Saravolacet al. (1991).J. Bacteriol.173, 4970–4976] and indicated extensive similarities in the single-channel conductance and glucose-binding properties of these two porins. Immunological and amino terminal sequence analysis revealed a high degree of homology. Of the first 14 amino terminal residues, 12 were identical. A major difference between the two porins was found in their ion selectivity. WhereasP. aeruginosa OprB is anion selective,P. putida OprB and other carbohydrate selective porins are known to be cation selective. |
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| Keywords: | Pseudomonas aeruginosa OprB glucose porin black lipid bilayer circular dichroism |
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