A G1127S change in calcium-binding epidermal growth factor-like domain 13 of human fibrillin-1 causes short range conformational effects.
Human fibrillin-1, an extracellular matrix glycoprotein, has a modular organization that includes 43 calcium-binding epidermal growth factor-like (cbEGF) domains arranged as multiple tandem repeats. A missense mutation that changes a highly conserved glycine to serine (G1127S) has been identified in cbEGF13, which results in a variant of Marfan syndrome, a connective tissue disease. Previous experiments on isolated cbEGF13 and a cbEGF13-14 pair indicated that the G1127S mutation caused defective folding of cbEGF13 but not cbEGF14. We have used limited proteolysis methods and two-dimensional NMR spectroscopy to identify the structural consequences of this mutation in a covalently linked cbEGF12-13 pair and a cbEGF12-14 triple domain construct. Protease digestion studies of the cbEGF12-13 G1127S mutant pair indicated that both cbEGF12 and 13 retained similar calcium binding properties and thus tertiary structure to the normal domain pair, because all identified cleavage sites showed calcium-dependent protection from proteolysis. However, small changes in the conformation of cbEGF13 G1127S, revealed by the presence of a new protease-sensitive site and comparative two-dimensional NOESY data, suggested that the fold of the mutant domain was not identical to the wild-type, but was native-like. Additional cleavage sites identified in cbEGF12-14 G1127S indicated further subtle changes within the mutant domain but not the flanking domains. We have concluded the following in this study. (i) Covalent linkage of cbEGF12 preserves the native-like fold of cbEGF13 G1127S and (ii) conformational effects introduced by G1127S are localized to cbEGF13. This study demonstrates that missense mutations in fibrillin-1 cbEGF domains can cause short range structural effects in addition to long range effects previously observed with a E1073K mutation in cbEGF12.
Divisions of Molecular and Cellular Biochemistry and Structural Biology, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
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Whiteman
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Smallridge
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Knott
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Cordle
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Downing
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Handford
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004815:Epidermal Growth Factor / Q000737:chemistry*; D016326:Extracellular Matrix Proteins / Q000737:chemistry; D000071838:Fibrillin-1; D000071837:Fibrillins; D014644:Genetic Variation; D005998:Glycine; D006801:Humans; D008382:Marfan Syndrome / Q000235:genetics; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D012694:Serine; D054392:Adipokines
D002118:Calcium; D004815:Epidermal Growth Factor; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071837:Fibrillins; D005998:Glycine; D008840:Microfilament Proteins; D011994:Recombinant Proteins; D012694:Serine; C000605722:FBN1 protein, human; D054392:Adipokines