Regulation of the cortical actin cytoskeleton in budding yeast by twinfilin, a ubiquitous actin monomer-sequestering protein

J Cell Biol. 1998 Aug 10;142(3):723-33. doi: 10.1083/jcb.142.3.723.

Abstract

Here we describe the identification of a novel 37-kD actin monomer binding protein in budding yeast. This protein, which we named twinfilin, is composed of two cofilin-like regions. In our sequence database searches we also identified human, mouse, and Caenorhabditis elegans homologues of yeast twinfilin, suggesting that twinfilins form an evolutionarily conserved family of actin-binding proteins. Purified recombinant twinfilin prevents actin filament assembly by forming a 1:1 complex with actin monomers, and inhibits the nucleotide exchange reaction of actin monomers. Despite the sequence homology with the actin filament depolymerizing cofilin/actin-depolymerizing factor (ADF) proteins, our data suggests that twinfilin does not induce actin filament depolymerization. In yeast cells, a green fluorescent protein (GFP)-twinfilin fusion protein localizes primarily to cytoplasm, but also to cortical actin patches. Overexpression of the twinfilin gene (TWF1) results in depolarization of the cortical actin patches. A twf1 null mutation appears to result in increased assembly of cortical actin structures and is synthetically lethal with the yeast cofilin mutant cof1-22, shown previously to cause pronounced reduction in turnover of cortical actin filaments. Taken together, these results demonstrate that twinfilin is a novel, highly conserved actin monomer-sequestering protein involved in regulation of the cortical actin cytoskeleton.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actin Depolymerizing Factors
  • Actins / metabolism
  • Actins / physiology*
  • Amino Acid Sequence
  • Binding, Competitive
  • Cytoplasm / metabolism
  • Cytoskeleton / chemistry
  • Cytoskeleton / physiology*
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / physiology*
  • Gene Deletion
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins
  • Microfilament Proteins / genetics
  • Microfilament Proteins / isolation & purification
  • Microfilament Proteins / metabolism
  • Microfilament Proteins / physiology*
  • Molecular Sequence Data
  • Protein-Tyrosine Kinases*
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / physiology*
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid

Substances

  • Actin Depolymerizing Factors
  • Actins
  • Fungal Proteins
  • Luminescent Proteins
  • Microfilament Proteins
  • Ptk9 protein, mouse
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • TWF1 protein, S cerevisiae
  • TWF1 protein, human
  • Green Fluorescent Proteins
  • Protein-Tyrosine Kinases