title: Cofilin weakly interacts with 14-3-3 and therefore can only indirectly participate in regulation of cell motility by small heat shock protein HspB6 (Hsp20).
abstract: It has been previously reported that phosphorylated cofilin interacted with 14-3-3ζ protein to generate a sub-micromolar K(d) binary complex. Here we challenge this hypothesis by analyzing the direct association of recombinant cofilin with 14-3-3ζ using different in vitro biochemical methods. Phosphorylated cofilin at high concentration binds to 14-3-3 immobilized on nitrocellulose, however no complex formation was detected by means of native gel electrophoresis or chemical crosslinking. Intact dimeric or mutant monomeric 14-3-3 was unable to form stable complexes with phosphorylated or unphosphorylated cofilin detected by size-exclusion chromatography. In co-sedimentation assay 14-3-3 did not affect interaction of cofilin with F-actin. The data of native gel electrophoresis indicate that 14-3-3 did not affect interaction of cofilin with G-actin. Thus, cofilin only weakly interacts with 14-3-3 and therefore cannot directly compete with phosphorylated small heat shock protein HspB6 for its binding to 14-3-3. It is hypothesized that phosphorylated HspB6 might affect interaction of 14-3-3 with protein phosphatases (and/or protein kinases) involved in dephosphorylation (or phosphorylation) of cofilin and by this means regulate cofilin-dependent reorganization of cytoskeleton.
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, Moscow 119991, Russian Federation.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Sudnitsyna
authors.forename: Alim S
authors.initials: AS
authors.lastname: Seit-Nebi
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Gusev
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D002465:Cell Movement / Q000502:physiology; D051338:Cofilin 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051340:Cofilin 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D050886:HSP20 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D000199:Actins; C495810:CFL1 protein, human; C495815:CFL2 protein, human; D051338:Cofilin 1; D051340:Cofilin 2; D017931:DNA Primers; D050886:HSP20 Heat-Shock Proteins; C494382:HSPB6 protein, human; D011994:Recombinant Proteins