Abstract
A 72-amino-acid chimeric protein, Chi1, was constructed from the N-terminal part of interleukin 8, IL-8-(1-53), and the C-terminal part of melanoma growth stimulatory activity, MGSA-(54-72). Chi1 protein showed receptor-binding specificity and biological activity similar, but not identical to IL-8 and decidedly different from MGSA. The structure of Chi1 was determined in solution by two-dimensional NMR and molecular-dynamics calculations. The structure resembled the structures of MGSA and IL-8 closely, containing a triple-stranded beta-sheet in the IL-8 part and an amphipathic alpha-helix in the MGSA part. Chi1 formed dimers at millimolar concentrations via the first strand from the N-terminus, analogous to IL-8 and MGSA. In contrast to the latter molecules, however, the alpha-helix of Chi1 did not pack against the beta-sheet part, but was an independent structural element. This structural difference could be explained mainly by the modulation of hydrophobic interactions between the helix and the rest of the protein in Chi1 as compared to IL-8 and MGSA. It is concluded that tight helix packing is not required for receptor binding and biological activity of Chi1.
MeSH terms
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Amino Acid Sequence
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Antigens, CD / genetics
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Antigens, CD / metabolism
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Binding Sites
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Cell Line
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Chemokine CXCL1
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Chemokines, CXC*
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Chemotactic Factors / chemistry*
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Chemotactic Factors / genetics
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Chemotactic Factors / metabolism*
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Growth Substances / chemistry*
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Growth Substances / genetics
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Growth Substances / metabolism*
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Hexosaminidases / metabolism
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Humans
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In Vitro Techniques
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Intercellular Signaling Peptides and Proteins*
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Interleukin-8 / chemistry*
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Interleukin-8 / genetics
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Interleukin-8 / metabolism*
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Magnetic Resonance Spectroscopy
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Models, Molecular
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Molecular Sequence Data
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Molecular Structure
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Neutrophils / drug effects
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Neutrophils / enzymology
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Protein Conformation
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Protein Structure, Secondary
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Receptors, Interleukin / genetics
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Receptors, Interleukin / metabolism
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Receptors, Interleukin-8A
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Sequence Homology, Amino Acid
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Thermodynamics
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Transfection
Substances
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Antigens, CD
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CXCL1 protein, human
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Chemokine CXCL1
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Chemokines, CXC
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Chemotactic Factors
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Growth Substances
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Intercellular Signaling Peptides and Proteins
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Interleukin-8
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Receptors, Interleukin
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Receptors, Interleukin-8A
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Recombinant Fusion Proteins
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Recombinant Proteins
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Hexosaminidases