Article
- The EMBO Journal (2004) 23, 3010 - 3019
- doi:10.1038/sj.emboj.7600310
Published online: 29 July 2004
Subject Category:
Biological role and structural mechanism of twinfilin–capping protein interaction
Sandra Falck1, Ville O Paavilainen1, Martin A Wear2, J Günter Grossmann3, John A Cooper2 and Pekka Lappalainen1
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Finland
- Department of Cell Biology and Physiology, Washington University, St Louis, MO, USA
- CCLRC Daresbury Laboratory, Synchrotron Radiation Department, Daresbury, Warrington, UK
Correspondence to:
Pekka Lappalainen, Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland. Tel.: +358 919 159499; Fax: +358 919 159366; E-mail: pekka.lappalainen@helsinki.fi
Received 5 May 2004; Accepted 14 June 2004
Abstract
Twinfilin and capping protein (CP) are highly conserved actin-binding proteins that regulate cytoskeletal dynamics in organisms from yeast to mammals. Twinfilin binds actin monomer, while CP binds the barbed end of the actin filament. Remarkably, twinfilin and CP also bind directly to each other, but the mechanism and role of this interaction in actin dynamics are not defined. Here, we found that the binding of twinfilin to CP does not affect the binding of either protein to actin. Furthermore, site-directed mutagenesis studies revealed that the CP-binding site resides in the conserved C-terminal tail region of twinfilin. The solution structure of the twinfilin–CP complex supports these conclusions. In vivo, twinfilin's binding to both CP and actin monomer was found to be necessary for twinfilin's role in actin assembly dynamics, based on genetic studies with mutants that have defined biochemical functions. Our results support a novel model for how sequential interactions between actin monomers, twinfilin, CP, and actin filaments promote cytoskeletal dynamics.
Keywords:
- actin,
- capping protein,
- twinfilin,
- yeast
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