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Asymmetric Mode of Ca²⁺-S100A4 Interaction with Nonmuscle Myosin IIA Generates Nanomolar Affinity Required for Filament Remodeling

Lookup NU author(s): Dr Martyna PastokORCiD

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Abstract

Filament assembly of nonmuscle myosin IIA (NMIIA) is selectively regulated by the small Ca²⁺-binding protein, S100A4, which causes enhanced cell migration and metastasis in certain cancers. Our NMR structure shows that an S100A4 dimer binds to a single myosin heavy chain in an asymmetrical configuration. NMIIA in the complex forms a continuous helix that stretches across the surface of S100A4 and engages the Ca²⁺-dependent binding sites of each subunit in the dimer. Synergy between these sites leads to a very tight association (K(D) ∼1 nM) that is unique in the S100 family. Single-residue mutations that remove this synergy weaken binding and ameliorate the effects of S100A4 on NMIIA filament assembly and cell spreading in A431 human epithelial carcinoma cells. We propose a model for NMIIA filament disassembly by S100A4 in which initial binding to the unstructured NMIIA tail initiates unzipping of the coiled coil and disruption of filament packing.

Publication metadata

Author(s): Elliott PR, Irvine AF, Jung HS, Tozawa K, Pastok MW, Picone R, Badyal SK, Basran J, Rudland PS, Barraclough R, Lian LY, Bagshaw CR, Kriajevska M, Barsukov IL

Publication type: Article

Publication status: Published

Journal: Structure

Year: 2012

Volume: 20

Issue: 4

Pages: 654-666

Print publication date: 04/04/2012

ISSN (print): 0969-2126

ISSN (electronic): 1878-4186

Publisher: Cell Press

URL: http://dx.doi.org/10.1016/j.str.2012.02.002

DOI: 10.1016/j.str.2012.02.002

PubMed id: PMC3343272

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