Molecular Characterization of Treponema pallidum mcp2, a Putative Chemotaxis Protein Gene

The nucleotide sequence of the Treponema pallidum mcp2 gene was determined. mcp2 encodes a 45.8-kDa protein whose deduced amino acid sequence has significant homology with the C-terminal region of bacterial methyl-accepting chemotaxis proteins (MCPs). The Mcp2 N terminus lacks the hydrophobic transmembrane regions present in most MCPs. An Mcp2 fusion protein was strongly reactive with antibody (HC23) to the highly conserved domain of MCPs and with rabbit syphilitic serum. Antibody HC23 reacted with six T. pallidum proteins, including a 45-kDa protein that may correspond to Mcp2. This protein was present in the aqueous phase from T. pallidum cells that were solubilized with Triton X-114 and phase partitioned.