Ion channel formation by N-terminal domain: a common feature of OprFs of Pseudomonas and OmpA of Escherichia coli

The proteolytic fragments of OprFs of Pseudomonas aeruginosa and Pseudomona s fluorescens were identified, respectively, as the first 175 and 177 amino acids from the N-terminal domain. They induced ion channels after reincorp oration into planar lipid bilayers (85 and 75 pS, respectively, in 1 M NaCl ). A similar conductance value (72 pS) was found for the eight beta-strand OmpA N-terminal domain (OmpA(171)) of Escherichia coli. We conclude that th e N-terminal domain of OprFs is sufficient to induce ion channels and the c omparison with OmpA(171), provides strong evidence of the existence of an e ight-stranded beta-barrel in the N-terminal domain of OprFs. (C) 2000 Feder ation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.