The purified major outer membrane protein (37275 Da) from the psychrotrophi
c phytopathogen Erwinia carotovora MFCL0 was structurally characterised by
MALDI-TOF mass spectrometry, N-terminal microsequencing and DNA sequence de
terminations, and secondary structure prediction analyses. The deduced amin
o acid sequence showed 76% and 72% of similarities with the Serratia marces
cens and Escherichia coli OmpA proteins respectively. Dendrogram analysis a
llowed to point out that E. carotovora is close to the genus Serratia. Afte
r reconstitution into planar lipid bilayers, this major protein induced ion
channels with a major conductance level of 630 pS in 1 M NaCl and a weak c
ationic selectivity. These functional and structural features allowed to id
entify this major outer membrane component of E. carotovora as an OmpA-like
protein, i.e., a channel-forming protein which could be involved in the in
fection process of this phytopathogen agent. (C) 2001 Elsevier Science B.V.
All rights reserved.