Cofilin and DNase I affect the conformation of the small domain of actin

Irina V. Dedova, Vadim N. Dedov, Neil J. Nosworthy, Brett D. Hambly, Cris G. Dos Remedios*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Cofilin binding induces an allosteric conformational change in subdomain 2 of actin, reducing the distance between probes attached to Gln-41 (subdomain 2) and Cys-374 (subdomain 1) from 34.4 to 31.4 Å (pH 6.8) as demonstrated by fluorescence energy transfer spectroscopy. This effect was slightly less pronounced at pH 8.0. In contrast, binding of DNase I increased this distance (35.5 Å), a change that was not pH-sensitive. Although DNase I-induced changes in the distance along the small domain of actin were modest, a significantly larger change (38.2 Å) was observed when the ternary complex of cofilin-actin-DNase I was formed. Saturation binding of cofilin prevents pyrene fluorescence enhancement normally associated with actin polymerization. Changes in the emission and excitation spectra of pyrene-F actin in the presence of cofilin indicate that subdomain 1 (near Cys-374) assumes a G-like conformation. Thus, the enhancement of pyrene fluorescence does not correspond to the extent of actin polymerization in the presence of cofilin. The structural changes in G and F actin induced by these actin-binding proteins may be important for understanding the mechanism regulating the G-actin pool in cells.

Original languageEnglish
Pages (from-to)3134-3143
Number of pages10
JournalBiophysical Journal
Issue number6
Publication statusPublished - Jun 2002
Externally publishedYes


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