THE IMMUNOREACTIVE 116 KDA SURFACE PROTEIN OF MYCOPLASMA-PNEUMONIAE IS ENCODED IN AN OPERON

Sera from 10 patients infected with Mycoplasma pneumoniae were used in Western blot analysis of Triton-X-114-soluble protein preparations of M. pneumoniae. All 10 sera were reactive with a protein antigen of 11 6 kDa. Sera from another 17 patients were used in Western blot analysi s of whole-cell M. pneumoniae proteins; 15 of these sera were reactive with the 116 kDa protein. Trypsin digestion of whole M. pneumoniae ce lls demonstrated the surface location of this protein. Sequencing of D NA which contained the gene for this protein identified an ORF of 3093 bp encoding a protein with a predicted molecular mass of 116013 Da. T he ORF for the 116 kDa protein had 99.8% nucleotide identity with the M. pneumoniae gene G07_orf1030 and 61% nucleotide identity with the My coplasma genitalium ORF MG075 of unassigned function. An ORF which was identified 5' to the 116 kDa protein ORF coded for a 16 kDa protein a nd had 99.8% nucleotide identity with the M. pneumoniae gene G07_orf13 5 and 58.4% nucleotide identity with the ORF MG074 of M. genitalium. A nalysis of mRNA detected a 3.7 kb transcript with a single initiation site 5' to the ORF encoding the 16 kDa protein. The coding sequences f or both the 16 kDa protein and the 116 kDa protein were present in thi s transcript, indicating that they were part of an operon and suggesti ng a possible functional relationship.