THE ADHESIN RELATED 30-KDA PROTEIN OF MYCOPLASMA-PNEUMONIAE EXHIBITS SIZE AND ANTIGEN VARIABILITY

Mycoplasma pneumoniae is a pathogenic bacterium colonizing epithelial cells of the human respiratory tract. Using an erythrocyte binding ass ay we isolated a cytadsorption negative mutant designated M7 which has lost 12 of a total of 13 repetitive sequences of a proline rich C-ter minal region of the adhesin related 30-kDa protein. The truncated adhe sin related protein of 22 kDa showed reduced antigenicity compared to the corresponding wild-type protein. Moreover, the mutant M7 proved in capable of adhering to erythrocytes and to a human colon carcinoma cel l fine indicating that the repetitive C-terminal region of the 30-kDa protein is essential for effective cytadherence. The adhesin related 3 0-kDa protein as well as the truncated forms of the corresponding prot ein were accessible to carboxypeptidase Y which clearly shows surface exposure of the C-terminus of this protein.