title: Human CC chemokine I-309, structural consequences of the additional disulfide bond.
abstract: I-309 is a member of the CC subclass of chemokines and is one of only three human chemokines known to contain an additional, third disulfide bond. The three-dimensional solution structure of I-309 was determined by (1)H nuclear magnetic resonance spectroscopy and dynamic simulated annealing. The structure of I-309, which remains monomeric at high concentrations, was determined on the basis of 978 experimental restraints. The N-terminal region of I-309 was disordered, as has been previously observed for the CC chemokine eotaxin but not others such as MCP-1 and RANTES. This was followed in I-309 by a well-ordered region between residues 13 and 69 that consisted of a 3(10)-helix, a triple-stranded antiparallel beta-sheet, and finally a C-terminal alpha-helix. Root-mean-square deviations of 0.61 and 1.16 were observed for the backbone and heavy atoms, respectively. A comparison of I-309 to eotaxin and HCC-2 revealed a significant structural change in the C-terminal region of the protein. The alpha-helix normally present in chemokines was terminated early and was followed by a short section of extended strand. These changes were a direct result of the additional disulfide bond present in this protein. An examination of the I-309 structure will aid in an understanding of the specificity of this protein with its receptor, CCR8.
authors.affiliation: Protein Engineering Network Centres of Excellence (PENCE) and Department of Biochemistry, 713 Heritage Medical Research Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
authors.forename: D W
authors.initials: DW
authors.lastname: Keizer
authors.forename: M P
authors.initials: MP
authors.lastname: Crump
authors.forename: T W
authors.initials: TW
authors.lastname: Lee
authors.forename: C M
authors.initials: CM
authors.lastname: Slupsky
authors.forename: I
authors.initials: I
authors.lastname: Clark-Lewis
authors.forename: B D
authors.initials: BD
authors.lastname: Sykes
mesh_terms: D000595:Amino Acid Sequence; D054402:Chemokine CCL1; D019742:Chemokines, CC / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry*; D006801:Humans; D019402:Macrophage Inflammatory Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015846:Monokines; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry; D017433:Protein Structure, Secondary; D012996:Solutions; D013329:Structure-Activity Relationship
chemical_list: C065971:CCL1 protein, human; C108814:CCL15 protein, human; D054402:Chemokine CCL1; D019742:Chemokines, CC; D004220:Disulfides; D019402:Macrophage Inflammatory Proteins; D015846:Monokines; D010446:Peptide Fragments; D012996:Solutions