The effects of formins on the conformation of subdomain 1 in actin filaments.
In this study we investigated the effects of formins on the conformation of actin filaments by using the method of fluorescence quenching. Actin was labelled with IAEDANS at Cys(374) and the quencher was acrylamide. The results showed that formin binding induced structural changes in the subdomain 1 of actin protomers which were reflected by greater quenching constants (K(SV)). Simultaneously the fraction of the fluorophore population accessible for the quencher (alpha) decreased. These observations suggest that the conformational distribution characteristic for the actin protomers became broader after the binding of formins, for which the structural framework was provided by a more flexible protein matrix in the microenvironment of the label. The effects of formins depended on the formin:actin molar ratio, and also on the ionic strength of the medium. These observations are in agreement with previous results and underline the importance of the intramolecular conformational changes induced by formins in the structure of actin filaments.
Ujfalusi
Zoltán
Z
University of Pécs, Faculty of Medicine, Department of Biophysics, Pécs, Szigeti str. 12, H-7624, Hungary.
Barkó
Szilvia
S
Hild
Gábor
G
Nyitrai
Miklós
M
D020106:Acrylamide / Q000737:chemistry; D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D000199:Actins / Q000737:chemistry*; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D000080865:Formins; D009282:Naphthalenesulfonates / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D013194:Staining and Labeling
D000199:Actins; D002352:Carrier Proteins; C491464:Diap1 protein, mouse; D005456:Fluorescent Dyes; D000080865:Formins; D009282:Naphthalenesulfonates; D020106:Acrylamide; C006421:1,5-I-AEDANS