Cloning and Sequencing of Two Type 4 (N-Methylphenylalanine) Pilin Genes from Eikenella Corrodens

Abstract

Eikenella corrodens is a Gram-negative microaerophilic rod which is gaining recognition as an important human pathogen. We have previously reported the cloning and expression in Escherichia coli of a 3.6 kb Eik. corrodens genomic DNA fragment which encodes a 31.5 kDa haemagglutinin. Maxicell analysis revealed that this fragment also encodes two proteins of approximately 14 kDa. Nucleotide sequencing of the 2.2 kb fragment upstream of the haemagglutinin gene revealed two open reading frames with strong homology to genes encoding pilin subunit proteins of the type 4 or N-methylphenylalanine class. The two pilin genes, ecpA and ecpB, are complete and are expressed in E. coli. Southern analysis of ten additional Eik. corrodens strains revealed that all possess fragments homologous to ecpA. These data represent the first molecular evidence for pili in E. corrodens.