Cloning and characterization of a major surface protein (MspTL) of Treponema lecithinolyticum associated with rapidly progressive periodontitis

The gene encoding a major surface protein (MspTL) of Treponema lecithinolyticum, a periodontopathogen, was cloned and sequenced. The mspTL gene has a 1770-bp open reading frame (ORF) encoding a protein of 590 amino acids with a predicted molecular mass of 65 kDa which had a typical prokaryotic signal sequence (19 amino acids). MspTL showed a high level of homology with major sheath protein (MspA) of Treponema maltophilum, phylogenetically the closest relative of T. lecithinolyticum. Southern blot analysis indicated that the mspTL gene exists in a single copy and Northern blot analysis showed that the mspTL transcript is monocistronic. Another ORF located downstream of mspTL was in the same orientation and encoded a putative protein, in which the first N-terminal 291 amino acids were identified. The homologous region of this protein is also a part on the T. maltophilum mspA locus.