title: Spectroscopic characterization of the effect of mouse twinfilin-1 on actin filaments at different pH values.
abstract: The effect of mammalian twinfilin-1 on the structure and dynamics of actin filaments were studied with steady state fluorescence spectroscopy, total internal reflection fluorescence microscopy and differential scanning calorimetry techniques. It was proved before that the eukaryotic budding yeast twinfilin-1 can efficiently bind and severe actin filaments in vitro at low pH values. In the present work steady-state anisotropy measurements revealed that twinfilin can bind efficiently to F-actin. Dilution-induced depolymerization assay proved that mammalian twinfilin-1 has an actin filament severing activity. This severing activity was more pronounced at low pH values. Total internal reflection fluorescence microscopy measurements could support the severing activity of mouse twinfilin-1. The average rate of depolymerization was more apparent at low pH values. The differential scanning calorimetry measurements demonstrated that mammalian twinfilin-1 could reduce the stiffness within the actin filaments before the detachment of the actin protomers. The structural and dynamic reorganization of actin can support the twinfilin-1 induced separation of actin protomers. The measured data indicated that mammalian twinfilin-1 was able to accelerate the monomers dissociation and/or sever the filaments effectively at low pH values. It was concluded that twinfilin-1 can affect the F-actin in biological processes or under stress situations when the pH is markedly under the physiological level.
authors.affiliation: University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti str. 12, H-7624, Hungary.
authors.forename: Veronika
authors.initials: V
authors.lastname: Takács-Kollár
authors.affiliation: University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti str. 12, H-7624, Hungary.
authors.forename: Dénes
authors.initials: D
authors.lastname: Lőrinczy
authors.affiliation: 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.
authors.forename: Miklós
authors.initials: M
authors.lastname: Nyitrai
authors.affiliation: University of Pécs, Medical School, Department of Biophysics, Pécs, Szigeti str. 12, H-7624, Hungary; University of Pécs, Medical School, Department of Radiology, Pécs, Ifjúság str. 13, H-7624, Hungary. Electronic address: gabor.hild@aok.pte.hu.
authors.forename: Gábor
authors.initials: G
authors.lastname: Hild
mesh_terms: D000818:Animals; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods*
chemical_list: D008840:Microfilament Proteins; C485190:Twf1 protein, mouse
keywords: Actin; Calorimetry; Cytoskeleton; Fluorescence; Spectroscopy; Twinfilin