title: C-terminal 15 kDa fragment of cytoskeletal actin is posttranslationally N-myristoylated upon caspase-mediated cleavage and targeted to mitochondria.
abstract: To detect the posttranslational N-myristoylation of caspase substrates, the susceptibility of the newly exposed N-terminus of known caspase substrates to protein N-myristoylation was evaluated by in vivo metabolic labeling with [(3)H]myristic acid in transfected cells using a fusion protein in which the query sequence was fused to a model protein. As a result, it was found that the N-terminal nine residues of the newly exposed N-terminus of the caspase-cleavage product of cytoskeletal actin efficiently direct the protein N-myristoylation. Metabolic labeling of COS-1 cells transiently transfected with cDNA coding for full-length truncated actin (tActin) revealed the efficient incorporation of [(3)H]myristic acid into this molecule. When COS-1 cells transiently transfected with cDNA coding for full-length actin were treated with staurosporine, an apoptosis-inducing agent, an N-myristoylated tActin was generated. Immunofluorescence staining coupled with MitoTracker or fluorescence tagged-phalloidin staining revealed that exogenously expressed tActin colocalized with mitochondria without affecting cellular and actin morphology. Taken together, these results demonstrate that the C-terminal 15 kDa fragment of cytoskeletal actin is posttranslationally N-myristoylated upon caspase-mediated cleavage during apoptosis and targeted to mitochondria.
authors.affiliation: Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. utsumi@agr.yamaguchi-u.ac.jp
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Utsumi
authors.forename: Nagisa
authors.initials: N
authors.lastname: Sakurai
authors.forename: Kengo
authors.initials: K
authors.lastname: Nakano
authors.forename: Rumi
authors.initials: R
authors.lastname: Ishisaka
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002522:Chlorocebus aethiops; D018260:Gelsolin / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D019814:Myristic Acid / Q000378:metabolism*; D010446:Peptide Fragments; D010957:Plasmids; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D018260:Gelsolin; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D019814:Myristic Acid; D020169:Caspases