The lppA gene, encoding the lipoprotein named LppA[Mcaca] was characterised in Mycoplasma
capricolum subsp. capricolum. It encodes a lipoprotein with an apparent molecular
mass of 57 kDa as determined by SDS-PAGE. Using antibodies directed against recombinant
LppA[Mcaca], we showed the expression of this lipoprotein in all M. capricolum subsp.
capricolum by immunoblot analysis. The serum did not cross-react with other members
of the Mycoplasma mycoides cluster, hence showing that LppA[Mcaca] was antigenically
specific to M. capricolum subsp. capricolum. The lppA gene was conserved within the
subspecies and was used for the development of a specific PCR assay for the identification
of M. capricolum subsp. capricolum. The taxonomically related Mycoplasma capricolum
subsp. capripneumoniae (F38) was found to contain an lppA-pseudo-gene. It showed high
similarity to functional lppA genes of other mycoplasmas in the M. mycoides cluster.
However, it contained interrupted open reading frames. Moreover, the nucleotide sequence
of the lppA pseudo-genes in different strains of M. capricolum subsp. capripneumoniae
were quite variable. Interestingly, the lppA pseudo-gene had a size similar to that
of the functional lppA genes of other mycoplasmas of the M. mycoides cluster and occupied
the same genomic location as the latter ones in the vicinity of the mtlD genes. This
study showed that all members of the M. mycoides cluster contain each a species-,
subspecies- respectively type- specific lppA gene analogue which encodes a lipoprotein
that has structural and functional relationship to the surface lipoprotein LppA [MmymySC],
previously named P72, of M. mycoides subsp mycoides SC, with the exception of M. capricolum
subsp. capripneumoniae which seems not to express an LppA analogue.