RRC ID 36626
Author Umeki N, Nakajima J, Noguchi TQ, Tokuraku K, Nagasaki A, Ito K, Hirose K, Uyeda TQ.
Title Rapid nucleotide exchange renders Asp-11 mutant actins resistant to depolymerizing activity of cofilin, leading to dominant toxicity in vivo.
Journal J Biol Chem
Abstract Conserved Asp-11 of actin is a part of the nucleotide binding pocket, and its mutation to Gln is dominant lethal in yeast, whereas the mutation to Asn in human α-actin dominantly causes congenital myopathy. To elucidate the molecular mechanism of those dominant negative effects, we prepared Dictyostelium versions of D11N and D11Q mutant actins and characterized them in vitro. D11N and D11Q actins underwent salt-dependent reversible polymerization, although the resultant polymerization products contained small anomalous structures in addition to filaments of normal appearance. Both monomeric and polymeric D11Q actin released bound nucleotides more rapidly than the wild type, and intriguingly, both monomeric and polymeric D11Q actins hardly bound cofilin. The deficiency in cofilin binding can be explained by rapid exchange of bound nucleotide with ATP in solution, because cofilin does not bind ATP-bound actin. Copolymers of D11Q and wild type actins bound cofilin, but cofilin-induced depolymerization of the copolymers was slower than that of wild type filaments, which may presumably be the primary reason why this mutant actin is dominantly toxic in vivo. Purified D11N actin was unstable, which made its quantitative biochemical characterization difficult. However, monomeric D11N actin released nucleotides even faster than D11Q, and we speculate that D11N actin also exerts its toxic effects in vivo through a defective interaction with cofilin. We have recently found that two other dominant negative actin mutants are also defective in cofilin binding, and we propose that the defective cofilin binder is a major class of dominant negative actin mutants.
Volume 288(3)
Pages 1739-49
Published 2013-1-18
DOI 10.1074/jbc.M112.404657
PII S0021-9258(20)46588-3
PMID 23212920
PMC PMC3548484
MeSH Actin Cytoskeleton / chemistry Actin Cytoskeleton / metabolism Actin Depolymerizing Factors / chemistry Actin Depolymerizing Factors / genetics Actin Depolymerizing Factors / metabolism* Actins / chemistry Actins / genetics Actins / metabolism* Adenosine Triphosphate / chemistry Adenosine Triphosphate / metabolism Aspartic Acid / chemistry Aspartic Acid / metabolism* Binding Sites Conserved Sequence Dictyostelium / genetics Dictyostelium / metabolism* Humans Kinetics Models, Molecular Mutation Nucleotides / genetics Nucleotides / metabolism* Plasmids Polymerization Protein Binding Protein Stability Protozoan Proteins / chemistry Protozoan Proteins / genetics Protozoan Proteins / metabolism* Saccharomyces cerevisiae / genetics Saccharomyces cerevisiae / metabolism Transfection
IF 4.238
Times Cited 11
Cellular slime molds