Thomas D D, Baseman J B, Alderete J F
J Exp Med. 1985 Nov 1;162(5):1715-9. doi: 10.1084/jem.162.5.1715.
The syphilis bacterium, Treponema pallidum, parasitizes host cells through recognition of fibronectin (Fn) on cell surfaces. The active site of the Fn molecule has been identified as a four-amino acid sequence, arg-gly-asp-ser (RGDS), located on each monomer of the cell-binding domain. The synthetic heptapeptide gly-arg-gly-asp-ser-pro-cys (GRGDSPC), with the active site sequence RGDS, specifically competed with 125I-labeled cell-binding domain acquisition by T. pallidum. Additionally, the same heptapeptide with the RGDS sequence diminished treponemal attachment to HEp-2 and HT1080 cell monolayers. Related heptapeptides altered in one key amino acid within the RGDS sequence failed to inhibit Fn cell-binding domain acquisition or parasitism of host cells by T. pallidum. The data support the view that T. pallidum cytadherence of host cells is through recognition of the RGDS sequence also important for eukaryotic cell-Fn binding.
梅毒螺旋体，苍白密螺旋体，通过识别细胞表面的纤连蛋白（Fn）寄生在宿主细胞上。Fn分子的活性位点已被确定为位于细胞结合域每个单体上的一个四氨基酸序列，即精氨酸-甘氨酸-天冬氨酸-丝氨酸（RGDS）。具有活性位点序列RGDS的合成七肽甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸-脯氨酸-半胱氨酸（GRGDSPC），能特异性地与梅毒螺旋体摄取的125I标记的细胞结合域竞争。此外，具有RGDS序列的同一七肽减少了梅毒螺旋体与HEp-2和HT1080细胞单层的附着。在RGDS序列内一个关键氨基酸发生改变的相关七肽未能抑制梅毒螺旋体摄取Fn细胞结合域或其对宿主细胞的寄生。这些数据支持这样一种观点，即梅毒螺旋体对宿主细胞的细胞粘附是通过识别RGDS序列实现的，而该序列对真核细胞与Fn的结合也很重要。
