f Molecular and biochemical analysis of a 105 kDa Mycoplasma gallisepticum cytadhesin(GapA)

SUMMARY: The identification of a gene (g8pA) from Mycoplasma gallisepticum with homology to the P I cytadherence gene of Mycoplasma pneumoniae is reported. The gapA gene is a 28 pORF encoding a protein with a molecular mass of 105 kDa. Nucleotide sequence analysis of the gapA gene revealed 45% homology t o the M. pneumoniae P I gene, 46% homology t o the Mycoplasma genitalium MgPa gene and 47% homology to the Mycoplasma pirum PI-like protein gene. It has a 64 mol% A+T content compared to 46,60 and 72 mol%respectively for the PI, MgPa and the Pl-like protein genes. As with the PI and MgPa genes, gapA is a central gene in a multi-gene operon, but unlike the P1 and MgPa genes, there is only a single copy of gapA in the genome. GapA is a trypsin-sensitive surface-exposed protein. Chicken tracheal-ring inhibition-of-attachment assays, using anti-GapA Fab fragments, resulted in 64% inhibition of attachment. These results indicated that GapA plays a rolein cytadherence of M. gallisepticum to host cells.