Interaction of formin FH2 with skeletal muscle actin. EPR and DSC studies.
Formins are highly conserved proteins that are essential in the formation and regulation of the actin cytoskeleton. The formin homology 2 (FH2) domain is responsible for actin binding and acts as an important nucleating factor in eukaryotic cells. In this work EPR and DSC were used to investigate the properties of the mDia1-FH2 formin fragment and its interaction with actin. MDia1-FH2 was labeled with a maleimide spin probe (MSL). EPR results suggested that the MSL was attached to a single SH group in the FH2. In DSC and temperature-dependent EPR experiments we observed that mDia1-FH2 has a flexible structure and observed a major temperature-induced conformational change at 41 °C. The results also confirmed the previous observation obtained by fluorescence methods that formin binding can destabilize the structure of actin filaments. In the EPR experiments the intermolecular connection between the monomers of formin dimers proved to be flexible. Considering the complex molecular mechanisms underlying the cellular roles of formins this internal flexibility of the dimers is probably important for manifestation of their biological functions.
Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs, 7624, Hungary.
Tünde
T
Kupi
Pál
P
Gróf
Miklós
M
Nyitrai
József
J
Belágyi
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002152:Calorimetry, Differential Scanning; D004578:Electron Spin Resonance Spectroscopy; D005326:Fetal Proteins / Q000737:chemistry*; D000080865:Formins; D006358:Hot Temperature; D008840:Microfilament Proteins / Q000737:chemistry*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry*; D011485:Protein Binding; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
D000199:Actins; D005326:Fetal Proteins; D000080865:Formins; D008840:Microfilament Proteins; D009687:Nuclear Proteins