Czimbalek Lívia, Kollár Veronika, Kardos Roland, Lőrinczy Dénes, Nyitrai Miklós, Hild Gábor
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary.
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary; Szentágothai Research Center, Pécs, Ifjúság Str. 34, H-7624, Hungary; MTA-PTE Nuclear-Mitochondrial Interactions Research Group, Pécs, Szigeti Str. 12, H-7624, Hungary.
FEBS Lett. 2015 Oct 7;589(20 Pt B):3085-9. doi: 10.1016/j.febslet.2015.08.038. Epub 2015 Sep 5.
The effects of toxofilin (an actin binding protein of Toxoplasma gondii) on G-actin was studied with spectroscopy techniques. Fluorescence anisotropy measurements proved that G-actin and toxofilin interact with 2:1 stoichiometry. The affinity of toxofilin to actin was also determined with a fluorescence anisotropy assay. Fluorescence quenching experiments showed that the accessibility of the actin bound ε-ATP decreased in the presence of toxofilin. The results can be explained by the shift of the nucleotide binding cleft into a closed conformational state. Differential scanning calorimetry measurements revealed that actin monomers become thermodynamically more stable due to the binding of toxofilin.
利用光谱技术研究了弓形虫肌动蛋白结合蛋白毒丝菌素对G-肌动蛋白的影响。荧光偏振测量证明，G-肌动蛋白和毒丝菌素以2:1的化学计量比相互作用。还通过荧光偏振测定法确定了毒丝菌素对肌动蛋白的亲和力。荧光猝灭实验表明，在毒丝菌素存在下，与肌动蛋白结合的ε-ATP的可及性降低。结果可以通过核苷酸结合裂隙转变为封闭构象状态来解释。差示扫描量热法测量表明，由于毒丝菌素的结合，肌动蛋白单体在热力学上变得更稳定。
