title: Assembly of a filamin four-domain fragment and the influence of splicing variant-1 on the structure.
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 β-strand of domain 19, FLNa(19), and the first β-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 β-strand and cause a rearrangement of the structure. Possible function roles for the spliced variants are discussed.
authors.affiliation: Department of Biological and Environmental Science and Nanoscience Center, P. O. Box 35, University of Jyväskylä, Jyväskylä FI-40014, Finland. ulla.m.pentikainen@jyu.fi
authors.forename: Ulla
authors.initials: U
authors.lastname: Pentikäinen
authors.forename: Pengju
authors.initials: P
authors.lastname: Jiang
authors.forename: Heikki
authors.initials: H
authors.lastname: Takala
authors.forename: Salla
authors.initials: S
authors.lastname: Ruskamo
authors.forename: Iain D
authors.initials: ID
authors.lastname: Campbell
authors.forename: Jari
authors.initials: J
authors.lastname: Ylänne
mesh_terms: D017398:Alternative Splicing; D003285:Contractile Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D064448:Filamins; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
chemical_list: D003285:Contractile Proteins; D064448:Filamins; D008840:Microfilament Proteins