Project description:The prokaryotic translation elongation factor P (EF-P), and the eukaryotic/archeal counterparts eIF5A/aIF5A, are proteins that serve a crucial role in mitigating ribosomal stalling during the translation of specific sequences, notably those containing consecutive proline residues. Although mitochondrial DNA-encoded proteins synthesized by mitochondrial ribosomes also contain polyproline stretches, an EF-P/eIF5A mitochondrial counterpart remains unidentified. Here, we show that the missing factor is the translational activator of COX1 (TACO1), a protein causative of a juvenile form of neurodegenerative Leigh's syndrome associated with cytochrome c oxidase deficiency. By using a combination of metabolic labeling, puromycin release, and ribosome profiling experiments, we show that TACO1 is required for the rapid synthesis of the poly-proline rich COX1 and COX3 proteins, while its requirement is negligible for other proteins. In agreement with a role in translation rate regulation, we show that TACO1 cooperates with the N-terminal extension of the large ribosomal subunit bL27m to provide stability to the peptidyl-transferase center during elongation, and that excess TACO1 enhances overall translation rate. We conclude that TACO1 is a Translation Accelerator and propose it as a promising target to regulate mitochondrial protein synthesis in disease scenarios.
Project description:Mitochondrial cytochrome c oxidase (CcO) or respiratory chain complex IV is a heme aa3-copper oxygen reductase containing metal centers essential for holo-complex biogenesis and enzymatic function that are assembled by subunit-specific metallochaperones. The enzyme has two copper sites located in the catalytic core subunits. The COX1 subunit harbors the CuB site that tightly associates with heme a3 while the COX2 subunit contains the binuclear CuA site. Here, we report that in human cells the CcO copper chaperones form macromolecular assemblies and cooperate with several twin CX9C proteins to control heme a biosynthesis and coordinate copper transfer sequentially to the CuA and CuB sites. These data on CcO illustrate a mechanism that regulates the biogenesis of macromolecular enzymatic assemblies with several catalytic metal redox centers and prevents the accumulation of cytotoxic reactive assembly intermediates. We characterized the proteome of COX11, COX19 and PET191 by AP + LC-MS-MS
Project description:Mitochondrial cytochrome c oxidase (CcO) or respiratory chain complex IV is a heme aa3-copper oxygen reductase containing metal centers essential for holo-complex biogenesis and enzymatic function that are assembled by subunit-specific metallochaperones. The enzyme has two copper sites located in the catalytic core subunits. The COX1 subunit harbors the CuB site that tightly associates with heme a3 while the COX2 subunit contains the binuclear CuA site. Here, we report that in human cells the CcO copper chaperones form macromolecular assemblies and cooperate with several twin CX9C proteins to control heme a biosynthesis and coordinate copper transfer sequentially to the CuA and CuB sites. These data on CcO illustrate a mechanism that regulates the biogenesis of macromolecular enzymatic assemblies with several catalytic metal redox centers and prevents the accumulation of cytotoxic reactive assembly intermediates. We characterized the proteome of COX11, COX19 and PET191 by AP + LC-MS-MS