SYNERGY BETWEEN ACTIN DEPOLYMERIZING FACTOR COFILIN AND PROFILIN IN INCREASING ACTIN FILAMENT TURNOVER

Citation
D. Didry et al., SYNERGY BETWEEN ACTIN DEPOLYMERIZING FACTOR COFILIN AND PROFILIN IN INCREASING ACTIN FILAMENT TURNOVER, The Journal of biological chemistry, 273(40), 1998, pp. 25602-25611
Citations number
31
Categorie Soggetti
Biology
ISSN journal
00219258
Volume
273
Issue
40
Year of publication
1998
Pages
25602 - 25611
Database
ISI
SICI code
0021-9258(1998)273:40<25602:SBADFC>2.0.ZU;2-L
Abstract
The mechanism of control of the steady state of actin assembly by acti n depolymerizing factor (ADF)/cofilin and profilin has been investigat ed. Using TP, as an indicator of the concentration of ATP-G-actin, we show that ADF increases the concentration of ATP-G-actin at steady sta te. The measured higher concentration of ATP-G-actin is quantitatively consistent with the increase in treadmilling, caused by the large inc rease in the rate of depolymerization from the pointed ends induced by ADF (Carlier, M.-F., Laurent, V., Santolini, J., Didry, D., Melki, R. , Xia, G.-X., Hong, Y., Chua, N.-H., and Pantaloni, D. (1997) J. Cell Biol. 136, 1307-1322). Experiments demonstrate that profilin synergize s with ADF to further enhance the turnover of actin filaments up to a value 125-fold higher than in pure F-actin solutions. Profilin and ADF act at the two ends of filaments in a complementary fashion to increa se the processivity of treadmilling. Using the capping protein CapZ, w e show that ADF increases the number of filaments at steady state by 1 .3-fold, which cannot account for the 25-fold increase in turnover rat e. Computer modeling of the combined actions of ADF and profilin on th e dynamics of actin filaments using experimentally determined rate con stants generates a distribution of the different actin species at stea dy state, which is in quantitative agreement with the data.