TY - JOUR
T1 - Two opposite effects of cofilin on the thermal unfolding of F-actin
T2 - a differential scanning calorimetric study
AU - Dedova, Irina V.
AU - Nikolaeva, Olga P.
AU - Mikhailova, Valeria V.
AU - dos Remedios, Cris G.
AU - Levitsky, Dmitrii I.
PY - 2004/7/1
Y1 - 2004/7/1
N2 - 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.
AB - 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.
KW - Actin
KW - ADF, actin depolymerizing factor
KW - Cofilin
KW - Differential scanning calorimetry
KW - DSC, differential scanning calorimetry.
KW - Thermal unfolding
UR - http://www.scopus.com/inward/record.url?scp=3042546532&partnerID=8YFLogxK
U2 - 10.1016/j.bpc.2004.01.009
DO - 10.1016/j.bpc.2004.01.009
M3 - Article
C2 - 15223149
AN - SCOPUS:3042546532
SN - 0301-4622
VL - 110
SP - 119
EP - 128
JO - Biophysical Chemistry
JF - Biophysical Chemistry
IS - 1-2
ER -