Characterization of the Cytochrome c Oxidase Assembly Factor Cox19 of Saccharomyces cerevisiae

Kevin Rigby,Limei Zhang,Paul A Cobine,Graham N George,Dennis R Winge

doi:10.1074/jbc.m610082200

Kevin Rigby, Limei Zhang + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m610082200

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Abstract

Cox19 is an important accessory protein in the assembly of cytochrome c oxidase in yeast. The protein is functional when tethered to the mitochondrial inner membrane, suggesting its functional role within the intermembrane space. Cox19 resembles Cox17 in having a twin CX(9)C sequence motif that adopts a helical hairpin in Cox17. The function of Cox17 appears to be a Cu(I) donor protein in the assembly of the copper centers in cytochrome c oxidase. Cox19 also resembles Cox17 in its ability to coordinate Cu(I). Recombinant Cox19 binds 1 mol eq of Cu(I) per monomer and exists as a dimeric protein. Cox19 isolated from the mitochondrial intermembrane space contains variable quantities of copper, suggesting that Cu(I) binding may be a transient property. Cysteinyl residues important for Cu(I) binding are also shown to be important for the in vivo function of Cox19. Thus, a correlation exists in the ability to bind Cu(I) and in vivo function.

Highlights

Of Cytochrome c oxidase (CcO) requires a myriad of steps, including the assembly of subunits translated on cytoplasmic and mitochondrial ribosomes, modification of protoheme to heme a, and the delivery and subsequent insertion of this moiety, along with that of copper into the nascent enzyme complex [2, 3]
One conformer consists of a single Cu(I) coordinated to a monomeric protein stabilized by two disulfide bonds [10]
The structural similarities of Cox19 with Cox17 suggested that Cox19 may function in the copper metallation of CcO

Summary

Introduction

Of CcO requires a myriad of steps, including the assembly of subunits translated on cytoplasmic and mitochondrial ribosomes, modification of protoheme to heme a, and the delivery and subsequent insertion of this moiety, along with that of copper into the nascent enzyme complex [2, 3]. Cox, and Cox are members of a conserved family of proteins containing a twin CX9C structural motif that adopts a helical hairpin conformation in Cox and the structural subunit Cox (6 – 8). These proteins have similar spacing of the four cysteinyl residues that form the two disulfide bonds in apoCox and apoCox12 [1, 8]. A mutant form of Cox lacking the remaining three conserved cysteines is functional, suggesting that Cox is functional without either of the two disulfides in the twin CX9C structural motif. Cysteine residues important for in vivo Cox function are important in Cu(I) coordination

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