Prevalence of novel repeat sequences in and around the P1 operon in the genome of Mycoplasma pneumoniae

The presence of numerous different repetitive elements in the genome of Mycoplasma pneumoniae has been documented by several laboratories. One which we previously identified, denoted as SDCI, has now been further characterized, verified to be distinct from those discussed in previous publications and shown to lack homology to several other species of Mycoplasma when tested under our stringency conditions. As many as eight versions of the SDCI-type repeat, which is more than 400 bp long, are scattered throughout the genome of M. pneumoniae. The prototype for SDCI is found within a gene encoding a putative 130-kDa membrane-binding protein lying just downstream from the gene encoding the cytadhesin protein P1. In fact, all of the reported M. pneumoniae repetitive elements have at least one representative either within or adjacent to the P1 operon; many if not all of these lie within open reading frames. The function of these repetitive elements is still unclear.