Mechanism of intestinal tight junction transmembrane proteins interaction with egg white peptides RVPSL and QIGLF

Previous work has indicated that the paracellular pathway is the main transport route of egg white peptides RVPSL (Arg-Val-Pro-Ser-Leu) and QIGLF (Gln-Ile-Gly-Leu-Phe). This transport is regulated by tight junction transmembrane proteins, which limit the paracellular absorption of these peptides through their extracellular loops (ECLs). However, the paracellular absorption mechanism of peptides RVPSL and QIGLF remains elusive. Thus, this paper aimed to clarify the interaction mechanism between tight junction transmembrane proteins (Claudin-4, Claudin-9, and Junctional Adhesion Molecule 1 [JAM-1]) and peptides (RVPSL and QIGLF) using molecular docking and molecular dynamic simulation. The results indicated that the binding domains of Claudin-4, Claudin-9, and JAM-1 were identified using the online tool POCASA 1.1. Residues Gln75, Asn149, Gln156, and Arg158 in Claudin-4; residues Lys31 and Glu48 in Claudin-9; and residues Ile127, Gln156, Gly158, and Pro161 in JAM-1 might play a vital role in the paracellular absorption of active peptides, and hydrogen bond was the main interaction force. Further, the analysis of root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), and solvent accessible surface area (SASA) suggested that the docking complexes exhibited good stability during the simulation. This study contributes valuable insights into the molecular mechanism of peptides RVPSL and QIGLF through intercellular space.