Metal ion dependency of microfibrils supports a rod-like conformation for fibrillin-1 calcium-binding epidermal growth factor-like domains.
J Mol Biol
; 276(5): 855-60, 1998 Mar 13.
Article
in En
| MEDLINE
| ID: mdl-9566191
ABSTRACT
The effects of the removal and replacement of divalent cations on the ultrastructure of 10 to 12 nm fibrillin-1-containing microfibrils have been studied, in order to investigate the conformation of fibrillin-1 calcium-binding epidermal growth factor-like (cbEGF-like) domains within the microfibril. The NMR structure of a covalently linked pair of cbEGF-like domains from fibrillin-1 recently identified a rigid rod-like conformation for the domain pair stabilised by interdomain calcium binding. This suggested that tandem arrays of fibrillin-1 cbEGF-like domains may adopt an extended conformation within a microfibril. If correct, then removal of bound calcium from fibrillin-1 would be expected to increase the flexibility of each cbEGF-like interdomain linkage, resulting in a decrease in the length of the interbead region of the microfibril (and thus a decrease in bead to bead periodicity), a concomitant increase in its diameter, and an overall increase in the flexibility of the microfibril. Our results show that removal of calcium by treatment with EGTA causes a large alteration of the microfibril structure, resulting in microfibrils with a reduced beaded periodicity, a disrupted interbead region and an increased overall flexibility. These effects are readily reversible by the re-addition of calcium (in the form of CaCl2), but not by the addition of magnesium (MgCl2). This is consistent with conformational changes in cbEGF-like domains causing the major structural effects on the microfibril. These results provide the first direct experimental evidence to support an extended rod-like conformation for multiple tandem repeats of fibrillin-1 cbEGF-like domains within the microfibril, as predicted by the NMR structure of an isolated fibrillin-1 cbEGF-like domain pair.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Actin Cytoskeleton
/
Microfilament Proteins
Type of study:
Prognostic_studies
Limits:
Humans
Language:
En
Journal:
J Mol Biol
Year:
1998
Type:
Article
Affiliation country:
United kingdom