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Comparison of the solution conformations of a cell-adhesive peptide LBE and its reverse sequence EBL
S D Jois1, R Hughes, T J Siahaan
1Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66047, USA.
Insights
Reversing the LBE peptide sequence to EBL did not significantly alter secondary structures, impacting its use as a biological control. This finding is crucial for designing better inhibitors of T-cell adhesion.
Area of Science:
- Biochemistry
- Structural Biology
- Immunology
Background:
- T-cell adhesion is vital for immune response, mediated by ICAM-1/LFA-1 interaction.
- The LBE peptide, derived from LFA-1, inhibits this adhesion.
- Understanding peptide conformation is key to developing targeted therapies.
Purpose of the Study:
- To investigate the solution conformations of LBE peptide and its reverse sequence (EBL).
- To assess the impact of sequence reversal on peptide structure and biological function.
- To inform the design of novel ICAM-1/LFA-1 interaction inhibitors.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy in aqueous and TFE/water solutions.
- Circular Dichroism (CD) spectroscopy.
- Molecular Dynamics (MD) simulations.
Main Results:
- Both LBE and EBL peptides adopted stable helical conformations in 40% TFE/water.
- CD indicated LBE had 30% helical content, while EBL had 20%.
- NMR and MD revealed stable helical structures within specific residue ranges for both peptides.
Conclusions:
- Reversing the LBE peptide sequence to EBL did not substantially alter its secondary structure.
- Caution is advised when using reverse peptides as controls in biological studies.
- This research enhances the design of ICAM-1/LFA-1 interaction inhibitors.
Abstract:
T-cell adhesion is mediated by an ICAM-1/LFA-1 interaction; this interaction plays a crucial role in T-cell activation during immune response. LBE peptide, which is derived from the beta-subunit of LFA-1, has been shown to inhibit ICAM-1/LFA-1-mediated T-cell adhesion. In this work, we studied the solution conformations of LBE peptide and its reverse sequence (EBL) by NMR, CD and molecular dynamics simulations. Reverse peptides have been used as controls in biological studies. The effect of reversing the sequence of LBE to EBL peptides on their respective conformations is important in understanding their biological properties in vitro or in vivo. The NMR studies for these peptides were carried out in water and in TFE/water solvent systems. In 40% TFE/water, both peptides exhibited helical conformation. CD studies suggested that the LBE exhibits 30% helical conformation, while the EBL exhibits 20% helical conformation. From the NMR and MD simulation studies, it was evident that the peptides exhibited a stable helical conformation; a stable helical structure was found at Leu6 to Leu15 for LBE and at Gly9 to Leu17 for EBL. The helical conformations of LBE and EBL may be in equilibrium with other possible conformers; the other conformers contain loop and turn structures. Both peptides bind to divalent cations because the LBE is derived from the cation-binding region of the LFA-1. This study shows that reversing the peptide sequence did not alter the secondary structure of the corresponding sequence. Hence, caution must be exercised when using reverse peptides as controls in biological studies. This report will improve our ability to design a better inhibitor of ICAM-1/LFA-1 interaction.
