TY - JOUR
T1 - Identification of Two Sites in Gelsolin with Different Sensitivities to Adenine Nucleotides
AU - Laham, L. E.
AU - Way, M.
AU - Yin, H. L.
AU - Janmey, P. A.
PY - 1995/11
Y1 - 1995/11
N2 - The affinity of monomeric actin for several actin‐binding proteins, including gelsolin, depends on adenine nucleotides. Gelsolin binds faster and with higher affinity to ADP‐actin than to ATP‐actin. Here, we show that the C‐terminal actin‐binding domain of gelsolin, which is required for filament nucleating activity but not for filament severing activity, contains the site that distinguishes between ATP‐actin and ADP‐actin monomers. In contrast, actin binding to the N‐terminal half of gelsolin depends on solution ATP concentrations, but not on the nucleotide (ATP or ADP) tightly bound in the cleft of the actin monomer. Binding is stronger in the absence of free nucleotide or in the presence of 0.5 mM ADP than in solutions containing 0.5 mM ATP. Complexes formed using different nucleotide concentrations differ in their filament‐severing activities as well as in their abilities to increase the fluorescence of 4‐chloro‐7‐nitrobenzeno‐2‐oxa‐1,3‐diazole‐labeled actin monomers. These results suggest that, at physiologic concentrations of nucleotides, both free and actin‐bound ATP may affect the binding of actin to its accessory proteins and that gelsolin, actin, or the gelsolin‐actin complex, contains a low‐affinity nucleotide‐binding site.
AB - The affinity of monomeric actin for several actin‐binding proteins, including gelsolin, depends on adenine nucleotides. Gelsolin binds faster and with higher affinity to ADP‐actin than to ATP‐actin. Here, we show that the C‐terminal actin‐binding domain of gelsolin, which is required for filament nucleating activity but not for filament severing activity, contains the site that distinguishes between ATP‐actin and ADP‐actin monomers. In contrast, actin binding to the N‐terminal half of gelsolin depends on solution ATP concentrations, but not on the nucleotide (ATP or ADP) tightly bound in the cleft of the actin monomer. Binding is stronger in the absence of free nucleotide or in the presence of 0.5 mM ADP than in solutions containing 0.5 mM ATP. Complexes formed using different nucleotide concentrations differ in their filament‐severing activities as well as in their abilities to increase the fluorescence of 4‐chloro‐7‐nitrobenzeno‐2‐oxa‐1,3‐diazole‐labeled actin monomers. These results suggest that, at physiologic concentrations of nucleotides, both free and actin‐bound ATP may affect the binding of actin to its accessory proteins and that gelsolin, actin, or the gelsolin‐actin complex, contains a low‐affinity nucleotide‐binding site.
KW - ATP
KW - actin
KW - gelsolin
KW - nucleotides
UR - http://www.scopus.com/inward/record.url?scp=0028792634&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028792634&partnerID=8YFLogxK
U2 - 10.1111/j.1432-1033.1995.001_c.x
DO - 10.1111/j.1432-1033.1995.001_c.x
M3 - Article
C2 - 8529627
AN - SCOPUS:0028792634
SN - 0014-2956
VL - 234
SP - 1
EP - 7
JO - European Journal of Biochemistry
JF - European Journal of Biochemistry
IS - 1
ER -