LAUSR

Semaphorin‐3A (Sema‐3A) is a chemorepellant protein with various biological functions, including kidney development. It interacts with a protein complex consisting of the receptors neuropilin‐1 (NRP‐1) and plexin‐A1. After acute kidney injury, Sema‐3A is overexpressed and secreted, leading to a loss of kidney function. The development of peptide inhibitors is a promising approach to modulate the interaction of Sema‐3A with its receptor NRP‐1. Few interaction points between these binding partners are known. However, an immunoglobulin‐like domain‐derived peptide of Sema‐3A has shown a positive effect on cell proliferation. To specify these interactions between the peptide inhibitor and the Sema‐3A–NRP‐1 system, the peptides were modified with the photoactivatable amino acids 4‐benzoyl‐l‐phenylalanine or photo‐l‐leucine by solid‐phase peptide synthesis. Activity was tested by an enzyme‐linked immunosorbent‐based binding assay, and crosslinking experiments were analyzed by Western blot and mass spectrometry, demonstrating a specific binding site of the peptide at Sema‐3A. The observed signals for Sema‐3A‐peptide interaction were found in a defined area of the Sema domain, which was also demonstrated to be involved in NRP‐1 binding. The presented data identified the interaction site for further development of therapeutic peptides to treat acute kidney injury by blocking the Sema‐3A–NRP‐1 interaction.