The effects of ADF/cofilin and profilin on the conformation of the ATP-binding cleft of monomeric actin

Roland Kardos, Kinga Pozsonyi, Elisa Nevalainen, Pekka Lappalainen, M. Nyitrai, G. Hild

Research output: Contribution to journalArticle

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Abstract

Actin depolymerizing factor (ADF)/cofilin and profilin are small actin-binding proteins, which have central roles in cytoskeletal dynamics in all eukaryotes. When bound to an actin monomer, ADF/cofilins inhibit the nucleotide exchange, whereas most profilins accelerate the nucleotide exchange on actin monomers. In this study the effects of ADF/cofilin and profilin on the accessibility of the actin monomer's ATP-binding pocket was investigated by a fluorescence spectroscopic method. The fluorescence of the actin bound 3-ATP was quenched with a neutral quencher (acrylamide) in steady-state and time dependent experiments, and the data were analyzed with a complex form of the Stern-Volmer equation. The experiments revealed that in the presence of ADF/cofilin the accessibility of the bound 3-ATP decreased, indicating a closed and more compact ATP-binding pocket induced by the binding of ADF/cofilin. In the presence of profilin the accessibility of the bound 3-ATP increased, indicating a more open and approachable protein matrix around the ATP-binding pocket. The results of the fluorescence quenching experiments support a structural mechanism regarding the regulation of the nucleotide exchange on actin monomers by ADF/cofilin and profilin.

Original languageEnglish
Pages (from-to)2335-2343
Number of pages9
JournalBiophysical Journal
Volume96
Issue number6
DOIs
Publication statusPublished - 2009

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Destrin
Profilins
Actin Depolymerizing Factors
Actins
Adenosine Triphosphate
Nucleotides
Fluorescence
Microfilament Proteins
Acrylamide
Eukaryota

ASJC Scopus subject areas

  • Biophysics

Cite this

The effects of ADF/cofilin and profilin on the conformation of the ATP-binding cleft of monomeric actin. / Kardos, Roland; Pozsonyi, Kinga; Nevalainen, Elisa; Lappalainen, Pekka; Nyitrai, M.; Hild, G.

In: Biophysical Journal, Vol. 96, No. 6, 2009, p. 2335-2343.

Research output: Contribution to journalArticle

Kardos, Roland ; Pozsonyi, Kinga ; Nevalainen, Elisa ; Lappalainen, Pekka ; Nyitrai, M. ; Hild, G. / The effects of ADF/cofilin and profilin on the conformation of the ATP-binding cleft of monomeric actin. In: Biophysical Journal. 2009 ; Vol. 96, No. 6. pp. 2335-2343.
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AU - Hild, G.

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