Biogenesis of the preprotein translocase of the outer mitochondrial membrane: protein kinase A phosphorylates the precursor of Tom40 and impairs its import
| Autor: | Nikolaus Pfanner, Oliver Schmidt, Bernard Guiard, Sanjana Rao, Chris Meisinger, Birgit Schönfisch, Angelika B. Harbauer |
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| Rok vydání: | 2012 |
| Předmět: |
Saccharomyces cerevisiae Proteins
Translocase of the outer membrane Biosynthesis and Biodegradation TIM/TOM complex Saccharomyces cerevisiae Mitochondrial Membrane Transport Proteins Mitochondrial membrane transport protein Mitochondrial Precursor Protein Import Complex Proteins Translocase Phosphorylation Protein Precursors Protein kinase A Molecular Biology biology Cell Biology Articles Cyclic AMP-Dependent Protein Kinases Cell biology Biochemistry Translocase of the inner membrane Mitochondrial Membranes biology.protein Casein kinase 2 Carrier Proteins Protein Processing Post-Translational Biogenesis |
| Zdroj: | Molecular Biology of the Cell |
| ISSN: | 1939-4586 |
| Popis: | The translocase of the outer mitochondrial membrane (TOM) is essential for the import of proteins into mitochondria. Cytosolic protein kinase A phosphorylates the precursor of the channel-forming protein Tom40 and inhibits its import into mitochondria, thus regulating the biogenesis of the protein entry gate of mitochondria. The preprotein translocase of the outer mitochondrial membrane (TOM) functions as the main entry gate for the import of nuclear-encoded proteins into mitochondria. The major subunits of the TOM complex are the three receptors Tom20, Tom22, and Tom70 and the central channel-forming protein Tom40. Cytosolic kinases have been shown to regulate the biogenesis and activity of the Tom receptors. Casein kinase 2 stimulates the biogenesis of Tom22 and Tom20, whereas protein kinase A (PKA) impairs the receptor function of Tom70. Here we report that PKA exerts an inhibitory effect on the biogenesis of the β-barrel protein Tom40. Tom40 is synthesized as precursor on cytosolic ribosomes and subsequently imported into mitochondria. We show that PKA phosphorylates the precursor of Tom40. The phosphorylated Tom40 precursor is impaired in import into mitochondria, whereas the nonphosphorylated precursor is efficiently imported. We conclude that PKA plays a dual role in the regulation of the TOM complex. Phosphorylation by PKA not only impairs the receptor activity of Tom70, but it also inhibits the biogenesis of the channel protein Tom40. |
| Databáze: | OpenAIRE |
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