TY - JOUR
T1 - pH regulation of the F-actin binding properties of Dictyostelium elongation factor 1α
AU - Edmonds, Brian T.
AU - Murray, John
AU - Condeelis, John
PY - 1995/6/23
Y1 - 1995/6/23
N2 - ABP50, an F-actin bundling protein from Dictyostelium, is also the protein synthesis co-factor, elongation factor 1α (EF1α). Concomitant with cAMP stimulation in Dictyostelium is a cytoplasmic alkalinization (Aerts, R. J., DeWit, R. J. W., and Van Lookeren Campagne, M. M. (1987) FEBS Lett. 220, 366- 370) and a redistribution of EF1α (Dharmawardhane, S., Demma, M., Yang, F., and Condeelis, J. (1991) Cell Motil. Cytoskel. 20, 279-288). In addition, others have shown a correlation between intracellular pH and the level of protein synthesis in Dictyostelium (Aerts, R. J., Durston, A. J., and Moolenaar, W. H. (1985) Cell 43, 653-657). The present study investigates the relationship between pH and the F-actin binding properties of EF1α. We found that increasing pH over the physiological range 6.2-7.8 causes a loss of EF1α-mediated F-actin bundling and single filament binding, with corresponding increases in the amount of free EF1α in vitro. Similar results also were obtained by cell fractionation and confocal immunofluorescence microscopy. The EF1α binding constant (K(d)) for F-actin is increased from 0.2 μM to > 2.2 μM over the same pH range. In addition, EF1α-induced actin bundle formation is freely reversible by changes in pH. Thus, pH may be a potent modulator of cytoarchitecture in Dictyostelium and may also influence mRNA translation rates by modifying the interactions between the protein synthetic machinery and the actin cytoskeleton.
AB - ABP50, an F-actin bundling protein from Dictyostelium, is also the protein synthesis co-factor, elongation factor 1α (EF1α). Concomitant with cAMP stimulation in Dictyostelium is a cytoplasmic alkalinization (Aerts, R. J., DeWit, R. J. W., and Van Lookeren Campagne, M. M. (1987) FEBS Lett. 220, 366- 370) and a redistribution of EF1α (Dharmawardhane, S., Demma, M., Yang, F., and Condeelis, J. (1991) Cell Motil. Cytoskel. 20, 279-288). In addition, others have shown a correlation between intracellular pH and the level of protein synthesis in Dictyostelium (Aerts, R. J., Durston, A. J., and Moolenaar, W. H. (1985) Cell 43, 653-657). The present study investigates the relationship between pH and the F-actin binding properties of EF1α. We found that increasing pH over the physiological range 6.2-7.8 causes a loss of EF1α-mediated F-actin bundling and single filament binding, with corresponding increases in the amount of free EF1α in vitro. Similar results also were obtained by cell fractionation and confocal immunofluorescence microscopy. The EF1α binding constant (K(d)) for F-actin is increased from 0.2 μM to > 2.2 μM over the same pH range. In addition, EF1α-induced actin bundle formation is freely reversible by changes in pH. Thus, pH may be a potent modulator of cytoarchitecture in Dictyostelium and may also influence mRNA translation rates by modifying the interactions between the protein synthetic machinery and the actin cytoskeleton.
UR - http://www.scopus.com/inward/record.url?scp=0029020353&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029020353&partnerID=8YFLogxK
U2 - 10.1074/jbc.270.25.15222
DO - 10.1074/jbc.270.25.15222
M3 - Article
C2 - 7797506
AN - SCOPUS:0029020353
SN - 0021-9258
VL - 270
SP - 15222
EP - 15230
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 25
ER -