Structural Analysis of a Novel Small Molecule Ligand Bound to the CXCL12 Chemokine

CXCL12 binds to CXCR4, promoting both chemotaxis of lymphocytes and metastasis of cancer cells. We previously identified small molecule ligands that bind CXCL12 and block CXCR4-mediated chemotaxis. We now report a 1.9 angstrom resolution X-ray structure of CXCL12 bound by such a molecule at a site normally bound by sY21 of CXCR4. The complex structure reveals binding hot spots for future inhibitor design and suggests a new approach to targeting CXCL12CXCR4 signaling in drug discovery.