A Structurally Altered D,L-Amino Acid TCR Transmembrane Peptide Interacts with the TCR
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- 作者：Francisco J. Quintana ; Doron Gerber ; Itai Bloch ; Irun R. Cohen ; Yechiel Shai
- 刊名：Biochemistry
- 出版年：2007
- 出版时间：March 6, 2007
- 年：2007
- 卷：46
- 期：9
- 页码：2317 - 2325
- 全文大小：275K
- 年卷期：v.46,no.9(March 6, 2007)
- ISSN：1520-4995
文摘
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
transmembrane peptide (CP) is recruited to the TCR complex and inhibits T-cell activation in vitro andin vivo, similarly to the wild-type CP peptide. Here we investigated the relative contributions of thesecondary structure of CP compared to its side chains in the association of CP with the TCR. We disruptedthe secondary structure of CP by replacing two positive residues, needed for the interaction of CP withthe TCR complex, by their D-enantiomers (2D-CP). Structure disruption was demonstrated by CD andFTIR spectroscopy, and molecular dynamics simulation in a bilayer environment. In vitro, 2D-CPcolocalized with the TCR (visualized with confocal microscopy), immunoprecipitated with TCR but notMHC I, and inhibited T-cell activation. The peptide was effective also in vivo: it inhibited adjuvantarthritis in rats and delayed type hypersensitivity in BALB/c mice. Moreover, 2D-CP manifested greaterimmunosuppressive activity than wild-type CP, both in vivo and in vitro, which can be attributed to thegreater 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 onside chain interactions than on a specific secondary structure. The new altered secondary structure probablydetermines how the Lys and the Arg are positioned with respect to each other, so they can interact withthe TM domain of the receptor. In clinical terms, the increased solubility and resistance to degradation ofD-stereoisomers might be exploited in the targeted inactivation of pathogenic signaling pathways such asthose arising from TCR-triggered activation of T-cells in immune-mediated disorders.
transmembrane peptide (CP) is recruited to the TCR complex and inhibits T-cell activation in vitro andin vivo, similarly to the wild-type CP peptide. Here we investigated the relative contributions of thesecondary structure of CP compared to its side chains in the association of CP with the TCR. We disruptedthe secondary structure of CP by replacing two positive residues, needed for the interaction of CP withthe TCR complex, by their D-enantiomers (2D-CP). Structure disruption was demonstrated by CD andFTIR spectroscopy, and molecular dynamics simulation in a bilayer environment. In vitro, 2D-CPcolocalized with the TCR (visualized with confocal microscopy), immunoprecipitated with TCR but notMHC I, and inhibited T-cell activation. The peptide was effective also in vivo: it inhibited adjuvantarthritis in rats and delayed type hypersensitivity in BALB/c mice. Moreover, 2D-CP manifested greaterimmunosuppressive activity than wild-type CP, both in vivo and in vitro, which can be attributed to thegreater 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 onside chain interactions than on a specific secondary structure. The new altered secondary structure probablydetermines how the Lys and the Arg are positioned with respect to each other, so they can interact withthe TM domain of the receptor. In clinical terms, the increased solubility and resistance to degradation ofD-stereoisomers might be exploited in the targeted inactivation of pathogenic signaling pathways such asthose arising from TCR-triggered activation of T-cells in immune-mediated disorders.