Isolation and characterisation of the major outer membrane protein of Erwinia carotovora

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.