Alanine scan of an immunosuppressive peptide (CP): analysis of structure-function relationships.
Core peptide is a hydrophobic peptide, the sequence of which is derived from the T-cell antigen receptor alpha-chain transmembrane region. Previous studies have shown that core peptide can inhibit T-cell-mediated immune responses both in vitro and in vivo. Here, we report the role each constituent amino acid plays within core peptide using an alanine scan and the amino acid effect on function using a biological antigen presentation assay. The biophysical behaviour of these analogues in model membranes was analysed using surface plasmon resonance studies and then binding correlated with T-cell function. Removal of any single hydrophobic amino acid between the two charged amino acids in core peptide (R, K) resulted in lower binding. Changing the overall net charge of core peptide, by removing either of the positively charged residues (R or K), had varying effects on peptide binding and IL-2 production. There was a direct correlation (ρ = 0.718) between peptide binding to model membranes and peptide ability to inhibit IL-2. Except for IL-2 inhibition, production of other T-cell cytokines such as GM-CSF, IFN-γ, IL-1α, IL-4, IL-5, IL-6, IL-10, IL-17 and T-cell antigen receptor alpha-chain was not detected using a fluorescent bead immunoassay. This study provides important structure-function relationships essential for further drug design.
Rheumatology Department, The University of Sydney/Westmead Hospital, Westmead 2145, NSW, Australia.
Laura
L
Raguine
Marina
M
Ali
Veronika
V
Bender
Eve
E
Diefenbach
Munikumar Reddy
MR
Doddareddy
David
D
Hibbs
Nicholas
N
Manolios
D000409:Alanine / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D057927:Hydrophobic and Hydrophilic Interactions; D007166:Immunosuppressive Agents / Q000737:chemistry* / Q000494:pharmacology; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D008567:Membranes, Artificial; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry* / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology; D017433:Protein Structure, Secondary; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
D007166:Immunosuppressive Agents; D007376:Interleukin-2; D008567:Membranes, Artificial; D009842:Oligopeptides; D010446:Peptide Fragments; D016693:Receptors, Antigen, T-Cell, alpha-beta; D000409:Alanine