C-Terminal Identification of AD74, a Proteolytic Product of Enterococcus faecalis Aggregation Substance: Application of Liquid Chromatography/Mass Spectrometry

Sexual aggregation involved in conjugative transfer of Enterococcus faecalis plasmid pADl is enhanced by the sex pheromone cADl, which is excreted from recipient cells. A membrane-anchored 137 kDa protein is a pADl-encoded aggregation substance designated asal, which is responsible for cell-cell contact and leads to the aggregation of cells. An AD74 protein is a proteolytic product corresponding to the N-terminal half of asal. The C-terminal of AD74 was identified as lysine at position 510 (K-510) by liquid chromatography/mass spectrometry (LC/MS): it indicates that asal is cleaved specifically between K-510 and G-511.