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FEBS Lett. 2003 Mar 27;539(1-3):37-44.

C-terminal 15 kDa fragment of cytoskeletal actin is posttranslationally N-myristoylated upon caspase-mediated cleavage and targeted to mitochondria.

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1
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. utsumi@agr.yamaguchi-u.ac.jp

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.

PMID:
12650923
DOI:
10.1016/s0014-5793(03)00180-7
[Indexed for MEDLINE]
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