Abstract
Differential scanning calorimetry was used to examine the effects of cofilin on the thermal unfolding of actin. Stoichiometric binding increases the thermal stability of both G- and F-actin but at sub-saturating concentrations cofilin destabilizes F-actin. At actin:cofilin molar ratios of 1.5-6 the peaks corresponding to stabilized (66-67°C) and destabilized (56-57°C) F-actin are observed simultaneously in the same thermogram. Destabilizing effects of sub-saturating cofilin are highly cooperative and are observed at actin:cofilin molar ratios as low as 100:1. These effects are abolished by the addition of phalloidin or aluminum fluoride. Conversely, at saturating concentrations, cofilin prevents the stabilizing effects of phalloidin and aluminum fluoride on the F-actin thermal unfolding. These results suggest that cofilin stabilizes those actin subunits to which it directly binds, but destabilizes F-actin with a high cooperativity in neighboring cofilin-free regions.
Original language | English |
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Pages (from-to) | 119-128 |
Number of pages | 10 |
Journal | Biophysical Chemistry |
Volume | 110 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 1 Jul 2004 |
Externally published | Yes |
Keywords
- Actin
- ADF, actin depolymerizing factor
- Cofilin
- Differential scanning calorimetry
- DSC, differential scanning calorimetry.
- Thermal unfolding