ANALYSIS OF A MYCOPLASMA-HOMINIS MEMBRANE-PROTEIN, P120

The monoclonal antibody mAb 26.7D generated against a clinical isolate of Mycoplasma hominis 7488 was shown to react with a surface-exposed epitope on a 120-kDa protein (P120). The gene encoding the protein was cloned and sequenced, and the transcriptional start point was determi ned by primer extension analysis. The gene contained an open reading f rame of 3237 bp encoding a peptide of 1079 amino acids with a deduced molecular mass of 123 kDa. A putative amino-terminal signal peptide an d cleavage site for signal peptidase II were found. This suggests that the protein was synthesized as a precursor with subsequent processing to a mature lipoprotein. Surface exposure was confirmed by immunoelec tron microscopy. mAb 26.7D reacted with 11 of 19 M. hominis strains. T he gene was, however, present in all strains.