Isolation, sequencing and expression of Bartonella henselae omp43 and predicted membrane topology of the deduced protein

The infection of and interaction of human endothelial cells with Bartonella henselae is one of the most interesting aspects of Bartonella-associated d isease. The gene encoding the 43 kDa B. henselae outer membrane protein (Om p43) that binds endothelial cells was cloned and sequenced. Sequence analys is revealed an open reading frame of 1206 nucleotides coding for a protein of 402 amino acids. Analysis of the deduced amino acid sequence shows 38% i dentity over the entire sequence to the Brucella spp. In addition to this O mp2b porin also shows a signal sequence and peptidase cleavage site. Cleava ge of the signal peptide results in a mature 380 amino acid polypeptide wit h a predicted molecular weight of 42 kDa. Omp43 was expressed in Escherichi a coli as a fusion protein. Purified recombinant Omp43 at concentrations of 11 and 2.75 mu g/ml bound to intact human umbilical vein endothelial cells . Membrane topology analysis predicts that Omp43 exists as a 16 stranded be ta barrel protein, similar to that predicted for the Omp2b Brucella abortus porin. Characterization and expression of the gene encoding Omp43 should p rovide a tool for further investigation of the role of adherence to endothe lial cells in the pathogenesis of B. henselae. (C) 2000 Academic Press.