A1 Refereed original research article in a scientific journal
Assembly of a Filamin Four-domain Fragment and the Influence of Splicing Variant-1 on the Structure
Authors: Pentikainen U, Jiang PJ, Takala H, Ruskamo S, Campbell ID, Ylanne J
Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Publication year: 2011
Journal: Journal of Biological Chemistry
Journal name in source: JOURNAL OF BIOLOGICAL CHEMISTRY
Journal acronym: J BIOL CHEM
Volume: 286
Issue: 30
First page : 26921
Last page: 26930
Number of pages: 10
ISSN: 0021-9258
DOI: https://doi.org/10.1074/jbc.M110.195958
Abstract
Filamins are scaffold proteins that bind to various proteins, including the actin cytoskeleton, integrin adhesion receptors, and adaptor proteins such as migfilin. Alternative splicing of filamin, largely constructed from 24 Ig-like domains, is thought to have a role in regulating its interactions with other proteins. The filamin A splice variant-1 (FLNa var-1) lacks 41 amino acids, including the last beta-strand of domain 19, FLNa(19), and the first beta-strand of FLNa(20) that was previously shown to mask a key binding site on FLNa(21). Here, we present a structural characterization of domains 18-21, FLNa(18-21), in the FLNa var-1 as well as its nonspliced counterpart. A model of nonspliced FLNa(18-21), obtained from small angle x-ray scattering data, shows that these four domains form an L-shaped structure, with one arm composed of a pair of domains. NMR spectroscopy reveals that in the splice variant, FLNa(19) is unstructured whereas the other domains retain the same fold as in their canonical counterparts. The maximum dimensions predicted by small angle x-ray scattering data are increased upon migfilin binding in the FLNa(18-21) but not in the splice variant, suggesting that migfilin binding is able to displace the masking beta-strand and cause a rearrangement of the structure. Possible function roles for the spliced variants are discussed.
Filamins are scaffold proteins that bind to various proteins, including the actin cytoskeleton, integrin adhesion receptors, and adaptor proteins such as migfilin. Alternative splicing of filamin, largely constructed from 24 Ig-like domains, is thought to have a role in regulating its interactions with other proteins. The filamin A splice variant-1 (FLNa var-1) lacks 41 amino acids, including the last beta-strand of domain 19, FLNa(19), and the first beta-strand of FLNa(20) that was previously shown to mask a key binding site on FLNa(21). Here, we present a structural characterization of domains 18-21, FLNa(18-21), in the FLNa var-1 as well as its nonspliced counterpart. A model of nonspliced FLNa(18-21), obtained from small angle x-ray scattering data, shows that these four domains form an L-shaped structure, with one arm composed of a pair of domains. NMR spectroscopy reveals that in the splice variant, FLNa(19) is unstructured whereas the other domains retain the same fold as in their canonical counterparts. The maximum dimensions predicted by small angle x-ray scattering data are increased upon migfilin binding in the FLNa(18-21) but not in the splice variant, suggesting that migfilin binding is able to displace the masking beta-strand and cause a rearrangement of the structure. Possible function roles for the spliced variants are discussed.
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