Complete crystal structure of monocyte chemotactic protein-2, a CC chemokine that interacts with multiple receptors.
Monocyte chemotactic protein 2 (MCP-2) is a CC chemokine that utilizes multiple cellular receptors to attract and activate human leukocytes. MCP-2 is a potent inhibitor of HIV-1 by virtue of its high-affinity binding to the receptor CCR5, one of the major coreceptors for HIV-1. Although a few structures of CC chemokines have been reported, none of these was determined with the N-terminal pyroglutamic acid residue (pGlu1) and a complete C-terminus. pGlu1 is essential for the chemotactic activity of MCP-2. Recombinant MCP-2 has Gln1 at the N terminus, 12-15% of which cyclizes automatically and forms pGlu1. The chemotactic activity of such MCP-2 mixture, which contains 12-15% pGlu1-form and 85-88% Gln1-form protein, is approximately 10 times lower when compared with that of fully cyclized MCP-2 preparation. Therefore, this chemokine is practically inactive without pGlu1. We have determined the complete crystal structure of MCP-2 that contains both pGlu1 and an intact C-terminus. With the existence of pGlu1, the conformation of the N-terminus allows two additional interactions between the two subunits of MCP-2 dimer: a hydrogen bond between pGlu1 and Asn17 and a salt bridge between Asp3 and Arg18. Consequently, both pGlu1 are anchored and buried, and thereby, both N-terminal regions are protected against protease degradation. We have also observed not previously reported extended helical nature of the C terminal region, which covers residues 58-74.
Blaszczyk
J
J
Program in Structural Biology and Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick, Maryland 21702, USA.
Coillie
E V
EV
Proost
P
P
Damme
J V
JV
Opdenakker
G
G
Bujacz
G D
GD
Wang
J M
JM
Ji
X
X
D000595:Amino Acid Sequence; D054412:Chemokine CCL8; D002633:Chemotaxis; D003460:Crystallization; D018360:Crystallography, X-Ray; D005973:Glutamine / Q000737:chemistry; D006801:Humans; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018945:Monocyte Chemoattractant Proteins / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D020033:Protein Isoforms / Q000737:chemistry; D017433:Protein Structure, Secondary; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry; D019707:Receptors, Chemokine / Q000378:metabolism*
C515453:CCL8 protein, human; D054412:Chemokine CCL8; D018945:Monocyte Chemoattractant Proteins; D010446:Peptide Fragments; D020033:Protein Isoforms; D019707:Receptors, Chemokine; D005973:Glutamine; D008239:Lysine; D011761:Pyrrolidonecarboxylic Acid