TY - JOUR
T1 - Cytochrome c oxidase subunit IV is essential for assembly and respiratory function of the enzyme complex
AU - Li, Youfen
AU - Park, Jeong Soon
AU - Deng, Janice J
AU - Bai, Yidong
N1 - Funding Information:
Acknowledgements This work was supported by grants from NIA/NIH (1 R01 AG025223-01) and from the American Heart Association (0430303-AHA). Yidong Bai is a New Scholar in Aging of the Ellison Medical Foundation. Xiufeng Song did some initial studies on this project. We thank Peiqing Hu for excellent technical assistance and Dr. Lily Dong for help with RNAi experiments.
PY - 2006/12
Y1 - 2006/12
N2 - Cytochrome c oxidase or complex IV, catalyzes the final step in mitochondrial electron transfer chain, and is regarded as one of the major regulation sites for oxidative phosphorylation. This enzyme is controlled by both nuclear and mitochondrial genomes. Among its 13 subunits, three are encoded by mitochondrial DNA and ten by nuclear DNA. In this work, an RNA interference approach was taken which led to the generation of mouse A9 cell derivatives with suppressed expression of nuclear-encoded subunit IV (COX IV) of this complex. The amounts of this subunit are decrease by 86% to 94% of normal level. A detail biosynthetic and functional analysis of several cell lines with suppressed COX IV expression revealed a loss of assembly of cytochrome c oxidase complex and, correspondingly, a reduction in cytochrome c oxidase-dependent respiration and total respiration. Furthermore, dysfunctional cytochrome c oxidase in the cells leads to a compromised mitochondrial membrane potential, a decreased ATP level, and failure to grow in galactose medium. Interestingly, suppression of COX IV expression also sensitizes the cells to apoptosis. These observations provide the evidence of the essential role of the COX IV subunit for a functional cytochrome c oxidase complex and also demonstrate a tight control of cytochrome c oxidase over oxidative phosphorylation. Finally, our results further shed some insights into the pathogenic mechanism of the diseases caused by dysfunctional cytochrome c oxidase complex.
AB - Cytochrome c oxidase or complex IV, catalyzes the final step in mitochondrial electron transfer chain, and is regarded as one of the major regulation sites for oxidative phosphorylation. This enzyme is controlled by both nuclear and mitochondrial genomes. Among its 13 subunits, three are encoded by mitochondrial DNA and ten by nuclear DNA. In this work, an RNA interference approach was taken which led to the generation of mouse A9 cell derivatives with suppressed expression of nuclear-encoded subunit IV (COX IV) of this complex. The amounts of this subunit are decrease by 86% to 94% of normal level. A detail biosynthetic and functional analysis of several cell lines with suppressed COX IV expression revealed a loss of assembly of cytochrome c oxidase complex and, correspondingly, a reduction in cytochrome c oxidase-dependent respiration and total respiration. Furthermore, dysfunctional cytochrome c oxidase in the cells leads to a compromised mitochondrial membrane potential, a decreased ATP level, and failure to grow in galactose medium. Interestingly, suppression of COX IV expression also sensitizes the cells to apoptosis. These observations provide the evidence of the essential role of the COX IV subunit for a functional cytochrome c oxidase complex and also demonstrate a tight control of cytochrome c oxidase over oxidative phosphorylation. Finally, our results further shed some insights into the pathogenic mechanism of the diseases caused by dysfunctional cytochrome c oxidase complex.
KW - ATP synthesis
KW - Apoptosis
KW - Complex IV assembly
KW - Cytochrome c oxidase complex
KW - Mitochondria
KW - Mitochondrial membrane potential
KW - Mitochondrial respiration
KW - RNA interference
KW - Subunit IV of complex IV
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U2 - 10.1007/s10863-006-9052-z
DO - 10.1007/s10863-006-9052-z
M3 - Article
C2 - 17091399
AN - SCOPUS:33845667921
VL - 38
SP - 283
EP - 291
JO - Journal of Bioenergetics and Biomembranes
JF - Journal of Bioenergetics and Biomembranes
SN - 0145-479X
IS - 5-6
ER -