Exploring the stereochemistry of CXCR4-peptide recognition and inhibiting HIV-1 entry with D-peptides derived from chemokines.
Chemokine receptor CXCR4 plays an important role in the immune system and the cellular entry of human immunodeficiency virus type 1 (HIV-1). To probe the stereospecificity of the CXCR4-ligand interface, d-amino acid peptides derived from natural chemokines, viral macrophage inflammatory protein II (vMIP-II) and stromal cell-derived factor-1alpha (SDF-1alpha), were synthesized and found to compete with (125)I-SDF-1alpha and monoclonal antibody 12G5 binding to CXCR4 with potency and selectivity comparable with or higher than their l-peptide counterparts. This was surprising because of the profoundly different side chain topologies between d- and l-enantiomers, which circular dichroism spectroscopy showed adopt mirror image conformations. Further direct binding experiments using d-peptide labeled with fluorescein (designated as FAM-DV1) demonstrated that d- and l-peptides shared similar or at least overlapping binding site(s) on the CXCR4 receptor. Structure-activity analyses of related peptide analogs of mixed chiralities or containing alanine replacements revealed specific residues at the N-terminal half of the peptides as key binding determinants. Acting as CXCR4 antagonists and with much higher biological stability than l-counterparts, the d-peptides showed significant activity in inhibiting the replication of CXCR4-dependent HIV-1 strains. These results show the remarkable stereochemical flexibility of the CXCR4-peptide interface. Further studies to understand the mechanism of this unusual feature of the CXCR4 binding surface might aid the development of novel CXCR4-binding molecules like the d-peptides that have high affinity and stability.
Zhou
Naiming
N
Kimmel Cancer Center and the Department of Biochemistry, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Luo
Zhaowen
Z
Luo
Jiansong
J
Fan
Xuejun
X
Cayabyab
Mark
M
Hiraoka
Megumi
M
Liu
Dongxiang
D
Han
Xiaobing
X
Pesavento
James
J
Dong
Chang-Zhi
CZ
Wang
Youli
Y
An
Jing
J
Kaji
Hideko
H
Sodroski
Joseph G
JG
Huang
Ziwei
Z
D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002460:Cell Line; D054377:Chemokine CXCL12; D054426:Chemokine CXCL2; D018925:Chemokines / Q000737:chemistry / Q000378:metabolism*; D019743:Chemokines, CXC / Q000378:metabolism; D002942:Circular Dichroism; D015497:HIV-1; D006801:Humans; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D015846:Monokines / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship
C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D054426:Chemokine CXCL2; D018925:Chemokines; D019743:Chemokines, CXC; D015846:Monokines; D019718:Receptors, CXCR4; D000409:Alanine