MOMP, a divergent porin from Campylobacter: Cloning and primary structuralcharacterization

We report a structural analysis at the molecular level of MOMP from Campylo bacter, a gram-negative bacteria responsible for diarrhea. The correspondin g gene was cloned and sequenced. Sequence comparison of seven MOMP sequence s (three extracted from protein databases and four determined in this study ) from distinct strains indicated alternation of preserved and divergent re gions. No other significant sequence similarities could be detected. Compar ison of MOMP with the crystal structures of other porins strongly suggested that it might adopt a similar fold and revealed the conservation of the mo nomer-monomer interface. The conservation clustered in the regions comprisi ng or interacting with the loop L2. On the contrary, strands not involved i n the interface are more divergent. Proteolysis assays and biochemical trea tment supported the proposed model. Our study suggested that MOMP belong to the maltoporin super-family sharing common structural motifs. In view of t his model we discuss its specificity and its global stability. (C) 2001 Aca demic Press.