Functional synergy of actin filament cross-linking proteins

Yiider Tseng, Benjamin W. Schafer, Steven C. Almo, Denis Wirtz

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

The organization of filamentous actin (F-actin) in resilient networks is coordinated by various F-actin cross-linking proteins. The relative tolerance of cells to null mutations of genes that code for a single actin cross-linking protein suggests that the functions of those proteins are highly redundant. This apparent functional redundancy may, however, reflect the limited resolution of available assays in assessing the mechanical role of F-actin cross-linking/bundling proteins. Using reconstituted F-actin networks and rheological methods, we demonstrate how α-actinin and fascin, two F-actin cross-linking/bundling proteins that co-localize along stress fibers and in lamellipodia, could synergistically enhance the resilience of F-actin networks in vitro. These two proteins can generate microfilament arrays that "yield" at a strain amplitude that is much larger than each one of the proteins separately. F-actin/α-actinin/fascin networks display strain-induced hardening, whereby the network "stiffens" under shear deformations, a phenomenon that is non-existent in F-actin/fascin networks and much weaker in F-actin/α-actinin networks. Strain-hardening is further enhanced at high rates of deformation and high concentrations of actin cross-linking proteins. A simplified model suggests that the optimum results of the competition between the increased stiffness of bundles and their decreased density of cross-links. Our studies support a re-evaluation of the notion of functional redundancy among cytoskeletal regulatory proteins.

Original languageEnglish (US)
Pages (from-to)25609-25616
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number28
DOIs
StatePublished - Jul 12 2002
Externally publishedYes

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Actin Cytoskeleton
Actins
Proteins
Actinin
Redundancy
Null Lymphocytes
Stress Fibers
Pseudopodia
Cytoskeletal Proteins
Strain hardening
Shear deformation
Hardening
Assays
Genes
Stiffness
Mutation
Fibers

ASJC Scopus subject areas

  • Biochemistry

Cite this

Functional synergy of actin filament cross-linking proteins. / Tseng, Yiider; Schafer, Benjamin W.; Almo, Steven C.; Wirtz, Denis.

In: Journal of Biological Chemistry, Vol. 277, No. 28, 12.07.2002, p. 25609-25616.

Research output: Contribution to journalArticle

Tseng, Yiider ; Schafer, Benjamin W. ; Almo, Steven C. ; Wirtz, Denis. / Functional synergy of actin filament cross-linking proteins. In: Journal of Biological Chemistry. 2002 ; Vol. 277, No. 28. pp. 25609-25616.
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