Eucaryotic cytochrome c oxidase, the terminal complex of the respiratory chain, is located in the mitochondrial inner membrane where it is assembled from both mitochondrially and nuclearly encoded subunits. Biosynthesis of this heteroligomeric complex requires the expression of a large number of nuclear genes whose products catalyze processing of the mitochondrial pre-mRNAs, translation of the mRNAs, and a host of post-translational events. At least a dozen such ancillary factors have been implicated to function at late stages of the assembly process, subsequent to synthesis, import and membrane insertion of all the catalytic and structural subunits. Most of our efforts during the prior grant period have been channeled towards attaining a better understanding of the biochemical lesions in assembly-defective mutants. As a result specific functions were ascribed to three proteins, one in heme A synthesis (Coxl0p) and two in mitochondrial copper homeostasis (Coxl7p, Sco1p). Several other mitochondrial proteins involved at post- translational stages of cytochrome oxidase assembly were also characterized. The present proposal has the following goals. 1) To reconstitute an in vitro system for studying copper transfer from Cox17p to Sco1p and subsequently to the apo-subunit 2 of cytochrome oxidase. These studies will make use of purified soluble Cox17p, liposome-bound Sco1p, and of submitochondrial particles containing unassembled subunit 2. 2) To study the kinetics of assembly of the constituent subunits by pulse-chase experiments. This technique will also be used to probe the stages at which enzyme assembly is blocked in mutants. 3) To screen for mutants in the terminal step of heme A synthesis. 4) To combine genetic and biochemical approaches in elucidating the functions of the gene products represented by the class of assembly-defective strains. Since the mechanism of cytochrome oxidase assembly is anticipated to be similar in all eucaryotes, information gained from these studies should be helpful in future analyses of human disorders stemming from cytochrome oxidase deficiencies.
| Su, Chen-Hsien; McStay, Gavin P; Tzagoloff, Alexander (2014) The Cox3p assembly module of yeast cytochrome oxidase. Mol Biol Cell 25:965-76 |
| McStay, Gavin P; Su, Chen Hsien; Tzagoloff, Alexander (2013) Stabilization of Cox1p intermediates by the Cox14p-Coa3p complex. FEBS Lett 587:943-9 |
| McStay, Gavin P; Su, Chen Hsien; Tzagoloff, Alexander (2013) Modular assembly of yeast cytochrome oxidase. Mol Biol Cell 24:440-52 |
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| Fontanesi, Flavia; Jin, Can; Tzagoloff, Alexander et al. (2008) Transcriptional activators HAP/NF-Y rescue a cytochrome c oxidase defect in yeast and human cells. Hum Mol Genet 17:775-88 |
| Zambrano, Andrea; Fontanesi, Flavia; Solans, Asun et al. (2007) Aberrant translation of cytochrome c oxidase subunit 1 mRNA species in the absence of Mss51p in the yeast Saccharomyces cerevisiae. Mol Biol Cell 18:523-35 |
| Barrientos, Antoni; Zambrano, Andrea; Tzagoloff, Alexander (2004) Mss51p and Cox14p jointly regulate mitochondrial Cox1p expression in Saccharomyces cerevisiae. EMBO J 23:3472-82 |
| Barros, Mario H; Johnson, Alisha; Tzagoloff, Alexander (2004) COX23, a homologue of COX17, is required for cytochrome oxidase assembly. J Biol Chem 279:31943-7 |
| Carlson, Christopher G; Barrientos, Antoni; Tzagoloff, Alexander et al. (2003) COX16 encodes a novel protein required for the assembly of cytochrome oxidase in Saccharomyces cerevisiae. J Biol Chem 278:3770-5 |
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