UL144-derived peptides as modulators of the BTLA/HVEM signaling pathway

BTLA HVEMFig. 1.The crystal structure of (A) BTLA/HVEM complex (PDB code: 2AW2), (B) alignment of both complexes and (C) BTLA/UL144 complex (PDB code: 6NYP). METHODS AND RESULTSTo define which amino acid residues of the UL144 protein are crucial for binding to BTLA, we performed the MM/GBSA analysis.The results showed that residues E26, Q33-P36, Y42, C48, and Q50-L58 in UL144 are significant for the interaction with BTLA (Fig. 2).According to ed et al., mutation of residue G46 to lysine (G46K) in the UL144 protein significantly increases binding affinity to BTLA, due to a new salt bridge formation [4].Considering the crystal structure of the BTLA/UL144 complex, MM/GBSA results and reference data, we designed eight peptides containing 0, 1, or 2 disulfide bonds -potential inhibitors of the BTLA/HVEM complex formation (Tab.1).The designed peptides were synthesized using solid-phase peptide synthesis (SPPS) and Fmoc/tBu strategy.The synthesis was conducted with an automated microwave peptide synthesizer (Liberty Blue, CEM Corporation).Peptides were then purified with RP-HPLC, oxidized to obtain disulfide bonds (except linear peptides), and purified again.