Purification and characterization of hemolysin from periodontopathogenic bacterium <i>Eikenella corrodens</i> strain 1073

<p><i>Eikenella corrodens</i> 1073 was found to show hemolytic activity when grown on sheep blood agar. A high and dose-dependent hemolytic activity was detected in the cell envelope fraction, which was further purified by ion-exchange and gel-filtration chromatography. Consequently, a 65-kDa protein with hemolytic activity was obtained, suggesting that this protein might be a hemolysin. Its N-terminal amino acid sequence was nearly identical to that of X-prolyl aminopeptidase from <i>E. corrodens</i> ATCC 23834. To confirm that X-prolyl aminopeptidase functions as a hemolytic factor, we expressed the <i>hlyA</i> gene, encoding X-prolyl aminopeptidase, in <i>Escherichia coli</i>. After induction with isopropyl β-D-1-thiogalactopyranoside, a protein of about 65 kDa was purified on a Ni column, and its hemolytic activity was confirmed. Meanwhile, a strain with a disrupted <i>hlyA</i> gene, which was constructed by homologous recombination, did not show any hemolytic activity. These results suggested that X-prolyl aminopeptidase might function as a hemolysin in <i>E. corrodens</i>.</p> <p><i>Eikenella corrodens</i> 1073 showed hemolytic activity when grown on sheep blood agar. We purified and identified the hemolytic factor.</p>