Lipid modification of the 15 kilo Dalton major membrane immunogen of Treponema pallidum |
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Authors: | B. K. Purcell M. A. Swancutt J. D. Radolf |
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Affiliation: | Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235. |
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Abstract: | The 15 kiloDalton major membrane immunogen was included among the Treponema pallidum polypeptides selectively labelled with [3H]-palmitate. The cloned gene for this immunogen, tpp15, encoded a signal peptide of 17 amino acids, a consensus signal peptidase II cleavage site, and a mature protein of 124 amino acids (13,967 Daltons). As predicted by the DNA sequence, the recombinant 15 kiloDalton immunogen labelled selectively with [3H]-palmitate, and globomycin inhibited processing of the precursor to the mature polypeptide. While the native and recombinant immunogens are amphiphilic, the 15 kiloDalton immunogen synthesized in a cell-free system was hydrophilic. The covalent attachment of fatty acids appears to be responsible for the amphiphilicity of the immunogen and its membrane attachment. |
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