IDENTIFICATION OF LACTOFERRIN-BINDING PROTEINS FROM TREPONEMA-PALLIDUM SUBSPECIES PALLIDUM AND TREPONEMA-DENTICOLA

Lactoferrin-binding or -associated proteins were identified in Trepone ma pallidum subspecies pallidum and Treponema denticola by affinity co lumn chromatography using human lactoferrin and detergent-solubilized, radiolabelled spirochaetes. Two discrete polypeptides of T. pallidum with masses of 45 and 40 kDa and a broad band from 29-34 kDa exhibited association with human apo- and partially ferrated lactoferrin. T. de nticola produced two proteins that associated with a lactoferrin affin ity matrix (50 and 35 kDa). T. pallidum and T. denticola did not assoc iate with soluble, human transferrin in parallel experiments. Soluble human lactoferrin competed with all lactoferrin-associated proteins fr om T. pallidum and T. denticola in competitive-binding assays. However , the T. denticola proteins dissociated from a lactoferrin-affinity ma trix in the presence of differing concentrations of unlabelled, solubl e lactoferrin competitor. Treatment with phospholipase D altered migra tion of the diffuse 29-34 kDa band of T. pallidum suggesting that the polypeptide was lipid-modified. Each of the lactoferrin-binding protei ns from T. pallidum and T. denticola reacted with pooled rabbit syphil itic antisera. The lactoferrin-binding proteins of T. pallidum reacted with human sera from patients at all stages of syphilis. In addition, a monoclonal antibody generated against the 45 kDa polypeptide of T. pallidum crossreacted with the 29-34 kDa protein.