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Actin depolymerizing factor stabilizes an existing state of F-actin and can change the tilt of F-actin subunits.

ABSTRACT: Proteins in the actin depolymerizing factor (ADF)/cofilin family are essential for rapid F-actin turnover, and most depolymerize actin in a pH-dependent manner. Complexes of human and plant ADF with F-actin at different pH were examined using electron microscopy and a novel method of image analysis for helical filaments. Although ADF changes the mean twist of actin, we show that it does this by stabilizing a preexisting F-actin angular conformation. In addition, ADF induces a large ( approximately 12 degrees ) tilt of actin subunits at high pH where filaments are readily disrupted. A second ADF molecule binds to a site on the opposite side of F-actin from that of the previously described ADF binding site, and this second site is only largely occupied at high pH. All of these states display a high degree of cooperativity that appears to be an integral part of F-actin.

SUBMITTER: Galkin VE

PROVIDER: S-EPMC2185532 | biostudies-literature | 2001 Apr

REPOSITORIES: biostudies-literature

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Actin depolymerizing factor stabilizes an existing state of F-actin and can change the tilt of F-actin subunits.

Galkin V E VE Orlova A A Lukoyanova N N Wriggers W W Egelman E H EH

The Journal of cell biology 20010401 1

Proteins in the actin depolymerizing factor (ADF)/cofilin family are essential for rapid F-actin turnover, and most depolymerize actin in a pH-dependent manner. Complexes of human and plant ADF with F-actin at different pH were examined using electron microscopy and a novel method of image analysis for helical filaments. Although ADF changes the mean twist of actin, we show that it does this by stabilizing a preexisting F-actin angular conformation. In addition, ADF induces a large ( approximate ...[more]

PMID: 11285275

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