The effect of toxofilin on the structure and dynamics of monomeric actin.
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.
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary.
Lívia
L
Czimbalek
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary.
Veronika
V
Kollár
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary.
Roland
R
Kardos
University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti Str. 12, H-7624, Hungary.
Dénes
D
Lőrinczy
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.
Miklós
M
Nyitrai
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. Electronic address: gabor.hild@aok.pte.hu.
Gábor
G
Hild
D051344:Actin Capping Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000465:Algorithms; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002152:Calorimetry, Differential Scanning; D005454:Fluorescence Polarization; D006358:Hot Temperature; D007700:Kinetics; D008956:Models, Chemical; D018482:Muscle, Skeletal / Q000378:metabolism; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011489:Protein Denaturation; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics; D044366:Transition Temperature
D051344:Actin Capping Proteins; D000199:Actins; D009711:Nucleotides; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C406004:toxofilin protein, Toxoplasma gondii
Actin; Calorimetry; Cytoskeleton; Dynamic; Fluorescence; Toxofilin