Solution structure and dynamics of a calcium binding epidermal growth factor-like domain pair from the neonatal region of human fibrillin-1.
Fibrillin-1 is a mosaic protein mainly composed of 43 calcium binding epidermal growth factor-like (cbEGF) domains arranged as multiple, tandem repeats. Mutations within the fibrillin-1 gene cause Marfan syndrome (MFS), a heritable disease of connective tissue. More than 60% of MFS-causing mutations identified are localized to cbEGFs, emphasizing that the native properties of these domains are critical for fibrillin-1 function. The cbEGF12-13 domain pair is within the longest run of cbEGFs, and many mutations that cluster in this region are associated with severe, neonatal MFS. The NMR solution structure of Ca(2+)-loaded cbEGF12-13 exhibits a near-linear, rod-like arrangement of domains. This observation supports the hypothesis that all fibrillin-1 (cb)EGF-cbEGF pairs, characterized by a single interdomain linker residue, possess this rod-like structure. The domain arrangement of cbEGF12-13 is stabilized by additional interdomain packing interactions to those observed for cbEGF32-33, which may help to explain the previously reported higher calcium binding affinity of cbEGF13. Based on this structure, a model of cbEGF11-15 that encompasses all known neonatal MFS missense mutations has highlighted a potential binding region. Backbone dynamics data confirm the extended structure of cbEGF12-13 and lend support to the hypothesis that a correlation exists between backbone flexibility and cbEGF domain calcium affinity. These results provide important insight into the potential consequences of MFS-associated mutations for the assembly and biomechanical properties of connective tissue microfibrils.
Smallridge
Rachel S
RS
Divisions of Structural Biology, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
Whiteman
Pat
P
Werner
Jörn M
JM
Campbell
Iain D
ID
Handford
Penny A
PA
Downing
A Kristina
AK
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000071838:Fibrillin-1; D000071837:Fibrillins; D006801:Humans; D020894:Microfibrils / Q000737:chemistry / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010641:Phenotype; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D054392:Adipokines
D002118:Calcium; D004815:Epidermal Growth Factor; D000071838:Fibrillin-1; D000071837:Fibrillins; D008840:Microfilament Proteins; C000605722:FBN1 protein, human; D054392:Adipokines