A structurally altered D,L-amino acid TCRα transmembrane peptide interacts with the TCRα and inhibits T-cell activation in vitro and in an animal model
A structurally altered D,L-amino acid TCRα transmembrane peptide interacts with the TCRα and inhibits T-cell activation in vitro and in an animal model
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DOI：
10.1021/bi061849g
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发表时间：
2007-03-06
期刊：
影响因子：
2.9
通讯作者：
Shai, Yechiel
中科院分区：
文献类型：
--
作者：
Quintana, Francisco J.;Gerber, Doron;Shai, Yechiel
细胞膜上的蛋白质-蛋白质相互作用是细胞对受体感知刺激的反应的关键。最近，已经证明TCR α跨膜肽（CP）的全D-氨基酸类似物被募集到TCR复合物中，并在体外和体内抑制T细胞活化，类似于野生型CP肽。在这里，我们研究了CP的二级结构的相对贡献相比，其侧链在协会的CP与TCR。我们通过将CP与TCR复合物相互作用所需的两个阳性残基替换为它们的D-对映体（2D-CP）来破坏CP的二级结构。通过CD和FTIR光谱以及双层环境中的分子动力学模拟证明了结构破坏。在体外，2D-CP与TCR共定位（用共聚焦显微镜观察），与TCR而不是MHC I免疫沉淀，并抑制T细胞活化。该肽在体内也是有效的：它抑制大鼠的佐剂性关节炎和BALB/c小鼠的迟发型超敏反应。此外，2D-CP表现出更大的免疫抑制活性比野生型CP，在体内和体外，这可以归因于更大的溶解度和抵抗降解的2D-CP。从分子角度来看，这些发现表明，在某些条件下，膜内蛋白质与蛋白质的相互作用可能更依赖于侧链相互作用，而不是特定的二级结构。新改变的二级结构可能决定了Lys和Arg如何相互定位，因此它们可以与受体的TM结构域相互作用。在临床方面，D-立体异构体增加的溶解度和对降解的抗性可用于靶向灭活致病性信号传导途径，例如免疫介导的疾病中由TCR触发的T细胞活化引起的那些。
Protein-protein interactions in the membrane are pivotal for the cellular response to receptor-sensed stimuli. Recently, it has been demonstrated that an all-D-amino acids analogue of the TCR alpha transmembrane peptide (CP) is recruited to the TCR complex and inhibits T-cell activation in vitro and in vivo, similarly to the wild-type CP peptide. Here we investigated the relative contributions of the secondary structure of CP compared to its side chains in the association of CP with the TCR. We disrupted the secondary structure of CP by replacing two positive residues, needed for the interaction of CP with the TCR complex, by their D-enantiomers (2D-CP). Structure disruption was demonstrated by CD and FTIR spectroscopy, and molecular dynamics simulation in a bilayer environment. In vitro, 2D-CP colocalized with the TCR (visualized with confocal microscopy), immunoprecipitated with TCR but not MHC I, and inhibited T-cell activation. The peptide was effective also in vivo: it inhibited adjuvant arthritis in rats and delayed type hypersensitivity in BALB/c mice. Moreover, 2D-CP manifested greater immunosuppressive activity than wild-type CP, both in vivo and in vitro, which can be attributed to the greater solubility and resistance to degradation of 2D-CP. In molecular terms, these findings suggest that, under certain conditions, protein-protein interactions within the membrane might be more dependent on side chain interactions than on a specific secondary structure. The new altered secondary structure probably determines how the Lys and the Arg are positioned with respect to each other, so they can interact with the TM domain of the receptor. In clinical terms, the increased solubility and resistance to degradation of D-stereoisomers might be exploited in the targeted inactivation of pathogenic signaling pathways such as those arising from TCR-triggered activation of T-cells in immune-mediated disorders.