SEQUENCE DIVERGENCE IN 2 TANDEMLY LOCATED PILIN GENES OF EIKENELLA-CORRODENS

Eikenella corrodens normally inhabits the human respiratory and gastro intestinal tracts but is frequently the cause of abscesses at various sites. Using the N-terminal portion of the Moraxella nonliquefaciens p ilin gene as a hybridization probe, we cloned two tandemly located pil in genes of E. corrodens 31745, ecpC and ecpD, and expressed the two p ilin genes separately in Escherichia coli. A comparison of the predict ed amino acid sequences of E. corrodens 31745 EcpC and EcpD revealed c onsiderable divergence between the sequences of these two pilins and e ven less similarity to EcpA and EcpB of E. corrodens type strain ATCC 23834. EcpC from E. corrodens 31745 displayed high degrees of homology to the pilins of Neisseria gonorrhoeae and Pseudomonas aeruginosa. Ec pD from E. corrodens 31745 showed the highest homologies with the pili n of one of the three P. aeruginosa classes, whereas EcpA and EcpB of strain ATCC 23834 most closely resemble Moraxella bovis pilins. These findings raise interesting questions about potential genetic transfer between different bacterial species, as opposed to convergent evolutio n.