PDBsum entry: 2hd7

Contractile protein

PDB id: 2hd7

Contents

Protein chain

142 a.a. *

* Residue conservation analysis

PDB id:

2hd7

Name:

Contractile protein

Title:

Solution structure of c-teminal domain of twinfilin-1.

Structure:

Twinfilin-1. Chain: a. Fragment: c-terminal domain, residues 176-316. Synonym: protein a6. Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Gene: ptk9. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

NMR struc:

15 models

Authors:

M.H.Hellman,V.O.Paavilainen,A.Annila,P.Lappalainen,P.I.Permi

Key ref:

V.O.Paavilainen et al. (2007). Structural basis and evolutionary origin of actin filament capping by twinfilin. Proc Natl Acad Sci U S A, 104, 3113-3118. PubMed id: 17360616 DOI: 10.1073/pnas.0608725104

Date:

20-Jun-06 Release date: 06-Feb-07

Protein chain

Q91YR1  (TWF1_MOUSE) -  Twinfilin-1

Seq: 350 a.a.

Struc: 142 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

 Gene Ontology (GO) functional annotation 

• Cellular component: intracellular (1 term)
• Biochemical function: actin binding (1 term)

DOI no: 10.1073/pnas.0608725104

Proc Natl Acad Sci U S A 104:3113-3118 (2007)

PubMed id: 17360616

Structural basis and evolutionary origin of actin filament capping by twinfilin.

V.O.Paavilainen, M.Hellman, E.Helfer, M.Bovellan, A.Annila, M.F.Carlier, P.Permi, P.Lappalainen.

ABSTRACT

Dynamic reorganization of the actin cytoskeleton is essential for motile and morphological processes in all eukaryotic cells. One highly conserved protein that regulates actin dynamics is twinfilin, which both sequesters actin monomers and caps actin filament barbed ends. Twinfilin is composed of two ADF/cofilin-like domains, Twf-N and Twf-C. Here, we reveal by systematic domain-swapping/inactivation analysis that the two functional ADF-H domains of twinfilin are required for barbed-end capping and that Twf-C plays a critical role in this process. However, these domains are not functionally equivalent. NMR-structure and mutagenesis analyses, together with biochemical and motility assays showed that Twf-C, in addition to its binding to G-actin, interacts with the sides of actin filaments like ADF/cofilins, whereas Twf-N binds only G-actin. Our results indicate that during filament barbed-end capping, Twf-N interacts with the terminal actin subunit, whereas Twf-C binds between two adjacent subunits at the side of the filament. Thus, the domain requirement for actin filament capping by twinfilin is remarkably similar to that of gelsolin family proteins, suggesting the existence of a general barbed-end capping mechanism. Furthermore, we demonstrate that a synthetic protein consisting of duplicated ADF/cofilin domains caps actin filament barbed ends, providing evidence that the barbed-end capping activity of twinfilin arose through a duplication of an ancient ADF/cofilin-like domain.

Selected figure(s)

Figure 3.
Fig. 3. A hybrid protein composed of two ADF/cofilins fused together by twinfilin's linker region caps actin-filament barbed ends. (A) The effects of 0 µM or 0.2 µM cofilin-2, and 0.2 µM cof-cof mutant on the bead motility in the absence of barbed-end capper. Addition of the cof-cof mutant, but not wild-type cofilin-2, restores actin tail formation and bead motility, confirming barbed-end capping by cof-cof. (B) Quantification of bead velocities at various cof-cof concentrations. The data are average velocities of at least 10 beads and their standard deviations.

Figure 4.
Fig. 4. A schematic model of gelsolin G1-G2- and twinfilin-capped actin filament barbed ends. (Left) The Holmes model of an actin filament (47) with G1-G2 from the G1-G3 actin monomer structure fitted onto the barbed end as presented in ref. 40. (Center) Schematic presentation of twinfilin's binding to F-actin is derived from the gelsolin-G-actin structure, gelsolin-F-actin and ADF/cofilin-G-actin models, and the mutagenesis data from this study for Twf-C and from ref. 28 for Twf-N. (Right) A model of interaction of twinfilin's "high-affinity" C-terminal ADF-H domain with actin monomer. The residues critical for G-actin binding identified in this study are highlighted in red.

Figures were selected by an automated process.