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Structure. 2006 Jan;14(1):43-50.

Dual requirement for flexibility and specificity for binding of the coiled-coil tropomyosin to its target, actin.

Author information

1
Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.

Abstract

The coiled coil is a widespread motif involved in oligomerization and protein-protein interactions, but the structural requirements for binding to target proteins are poorly understood. To address this question, we measured binding of tropomyosin, the prototype coiled coil, to actin as a model system. Tropomyosin binds to the actin filament and cooperatively regulates its function. Our results support the hypothesis that coiled-coil domains that bind to other proteins are flexible. We made mutations that alter interface packing and stability as well as mutations in surface residues in a postulated actin binding site. Actin affinity, measured by cosedimentation, was correlated with coiled-coil stability and local instability and side chain flexibility, analyzed with circular dichroism and fluorescence spectroscopy. The flexibility from interruptions in the stable coiled-coil interface is essential for actin binding. The surface residues in a postulated actin binding site participate in actin binding when the coiled coil within it is poorly packed.

PMID:
16407064
DOI:
10.1016/j.str.2005.09.016
[Indexed for MEDLINE]
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