Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Poster Abstracts

60-POS

Board 60

IN SILICO STUDY OF VIP AND PACAP INTERACTIONS WITH THEIR MEMBRANE RECEPTORS AIMING AT NEUROPEPTIDE OPTIMIZATION FOR HIV-1 INHIBITION IN MACROPHAGES Fernando Augusto T P Meireles 1 ; Ernesto R Caffarena 1 ; Deborah Antunes 1 ; Dumith C Bou Habib 2 ; Jairo R Temerozo 2 ; 1 Oswaldo Cruz Foundation (FIOCRUZ), Scientific Computation Program (PROCC), Rio de Janeiro, Brazil 2 Oswaldo Cruz Foundation (FIOCRUZ), Immunology Department, Rio de Janeiro, Brazil Vasoactive Intestinal Peptide (VIP) and Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) are neuropeptides of the glucagon/secretin family of high similarity. They act through interactions with the Vasoactive Intestinal Peptide Receptors 1 and 2 (VPAC1 and VPAC2) and the Pituitary Adenylate Cyclase-Activating Polypeptide Receptor type 1 (PAC1). In the scope of their functions, recent studies have demonstrated the capacity of VIP and PACAP to inhibit replication of HIV-1 in infected macrophages partially. This work aims to build, "in silico", the six possible peptide-receptor interaction systems and to identify hot-spots responsible for their stability. Molecular Modeling, Docking and Molecular Dynamics methods will be applied. Once the dissociation constants of the ligands are estimated, the most promising system will be optimized through Protein Engineering aiming at developing a mutant neuropeptide with higher affinity for one of the receptors, thus increasing its anti-HIV potential. Results from the PACAP/PAC1 system, obtained through comparative modeling using the software MODELLER 9.21, suggest the formation of several H-bonds and salt bridges between the C- terminal of the neuropeptide and the membrane receptor. The analysis package from the software Visual Molecular Dynamics (VMD) shows that PACAP residues Arg-30, Lys-32, Arg-34 and Asn-37 form H-bonds and Lys-29, Lys-32 and Arg-34 form salt bridges. The relevance of some of these interactions was indicated by hot-spots prediction server KFC2, which identified residues Ala-18, Tyr-22, Arg-30, Tyr-31, Gln-33, Arg-34, Val-35, Lys-36, Asn-37 and Lys-38 as hot-spots. Even though the interactions in the static model may hint to the actual "in vivo" interface conformation, molecular dynamics are necessary to determine the stability of these bonds.

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