TY - JOUR
T1 - A cluster of basic repeats in the dystrophin rod domain binds F-actin through an electrostatic interaction
AU - Amann, Kurt J.
AU - Renley, Brian A.
AU - Ervasti, James M.
PY - 1998/10/23
Y1 - 1998/10/23
N2 - The dystrophin rod domain is composed of 24 spectrin-like repeats and was thought to act mainly as a flexible spacer between the amino-terminal actin binding domain and carboxyl-terminal membrane-associated domains. We previously demonstrated that a fragment of the dystrophin rod domain also binds F-actin. However, the nature and extent of rod domain association with F-actin is presently unclear. To begin addressing these questions, we characterized two recombinant proteins representing adjacent regions of the dystrophin rod. DYS1416 (amino acids 1416-1880) bound F-actin with a K(d) of 14.2 ± 5.2 μM and a stoichiometry of 1 mol:mol of actin. However, DYS1030 (amino acids 10301494) failed to bind F-actin, suggesting that not all rod domain repeats are capable of binding F-actin. Interestingly, DYS1416 corresponds to a unique region of the dystrophin rod rich in basic amino acids, whereas DYS1030 is composed mainly of acidic repeats. This observation suggested that DYS1416 may interact with acidic actin filaments through an electrostatic interaction. Supporting this hypothesis, actin binding by DYS 1416 was dramatically inhibited by increasing ionic strength. We suggest that electrostatic interactions between basic spectrin-like repeats and actin filaments may contribute to the actin binding activity of other members of the actin cross-linking protein family.
AB - The dystrophin rod domain is composed of 24 spectrin-like repeats and was thought to act mainly as a flexible spacer between the amino-terminal actin binding domain and carboxyl-terminal membrane-associated domains. We previously demonstrated that a fragment of the dystrophin rod domain also binds F-actin. However, the nature and extent of rod domain association with F-actin is presently unclear. To begin addressing these questions, we characterized two recombinant proteins representing adjacent regions of the dystrophin rod. DYS1416 (amino acids 1416-1880) bound F-actin with a K(d) of 14.2 ± 5.2 μM and a stoichiometry of 1 mol:mol of actin. However, DYS1030 (amino acids 10301494) failed to bind F-actin, suggesting that not all rod domain repeats are capable of binding F-actin. Interestingly, DYS1416 corresponds to a unique region of the dystrophin rod rich in basic amino acids, whereas DYS1030 is composed mainly of acidic repeats. This observation suggested that DYS1416 may interact with acidic actin filaments through an electrostatic interaction. Supporting this hypothesis, actin binding by DYS 1416 was dramatically inhibited by increasing ionic strength. We suggest that electrostatic interactions between basic spectrin-like repeats and actin filaments may contribute to the actin binding activity of other members of the actin cross-linking protein family.
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U2 - 10.1074/jbc.273.43.28419
DO - 10.1074/jbc.273.43.28419
M3 - Article
C2 - 9774469
AN - SCOPUS:0032561199
SN - 0021-9258
VL - 273
SP - 28419
EP - 28423
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 43
ER -