The seventh transmembrane domain of cc chemokine receptor 5 is critical for MIP-1beta binding and receptor activation: role of MET 287.
CC chemokine receptor 5 (CCR5) is a high-affinity receptor for macrophage inflammatory protein (MIP)-1beta and functions as the major coreceptor for entry of macrophage-tropic (M-tropic) human immunodeficiency virus type 1 (HIV-1). To evaluate the role of transmembrane domains (TM) in the receptor function of CCR5, the seventh transmembrane domain (TM7) was examined in a series of chimeric receptor constructs including CCR5TM (CCR5 backbone/CCR5 TM7 replaced with CCR1 TM7) and mutants of CCR5TM. The CCR5TM chimera exhibited a dramatic reduction in receptor activation, as well as little or no MIP-1beta binding. Further mutational analysis revealed that Met 287 in TM7 of CCR5 is a critical molecular determinant for both MIP-1beta binding and receptor activation. Interestingly, all of the chimeric/mutated receptors were biologically active in an HIV-1 coreceptor fusion assay, demonstrating that chemokine binding is independent of HIV-1 coreceptor activity.
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, 46202
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Youn
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Yu
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Alkhatib
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Kwon
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D054407:Chemokine CCL4; D017931:DNA Primers; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D019713:Receptors, CCR5 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D054407:Chemokine CCL4; D017931:DNA Primers; D019402:Macrophage Inflammatory Proteins; D019713:Receptors, CCR5; D008715:Methionine