Structural and functional study of the apelin-13 peptide, an endogenous ligand of the HIV-1 coreceptor, APJ.
The APJ receptor is widely expressed in the human central nervous system (CNS). Apelin was recently identified as the endogenous peptidic ligand for human APJ. Studies with animal models suggested that APJ and apelin play an important role in the hypothalamic regulation of water intake and the endocrine axis, in the regulation of blood pressure, and in cardiac contractility. Apelin has been found to block the activity of APJ as a human immunodeficiency virus type I (HIV-1) coreceptor. In this study, we combined chemical synthetic approaches with alanine substitution to evaluate the structural requirements for interactions with the APJ receptor. We demonstrated that apelin peptides in aqueous solution adopt a random conformation, and the positive charge and hydrophobic residues of apelin-13 play important roles in interactions with the APJ receptor. We have observed an important correlation between receptor binding affinity and cell-cell fusion inhibitory activity. The elucidation of structural requirements of apelin-13 in its interaction with the APJ receptor is critical for further investigation of apelin-APJ functions in vivo and in the design of small molecular inhibitors for potential treatment of HIV-1 infection in the CNS.
Fan
Xuejun
X
Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Zhou
Naiming
N
Zhang
Xiaoling
X
Mukhtar
Muhammad
M
Lu
Zhixian
Z
Fang
Jianhua
J
DuBois
Garrett C
GC
Pomerantz
Roger J
RJ
D000409:Alanine / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000073861:Apelin; D000075244:Apelin Receptors; D001667:Binding, Competitive; D015704:CD4 Antigens / Q000235:genetics; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D015497:HIV-1 / Q000737:chemistry*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008156:Luciferases / Q000235:genetics; D008561:Membrane Fusion / Q000187:drug effects; D008856:Microscopy, Fluorescence; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017448:Receptors, Dopamine D2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D011991:Receptors, Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
C115436:APLN protein, human; C104575:APLNR protein, human; D000073861:Apelin; D000075244:Apelin Receptors; D015704:CD4 Antigens; D002352:Carrier Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled; D011991:Receptors, Virus; D008156:Luciferases; D000409:Alanine; D002118:Calcium