期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
卷 1709, 期 2, 页码 169-180出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbabio.2005.07.002
关键词
mitochondria; hypoxia; cytochrome oxidase isozyme; oxygen sensing
资金
- NIGMS NIH HHS [GM30228] Funding Source: Medline
Previous studies have demonstrated that the mitochondrial respiratory chain and cytochrome c oxidase participate in oxygen sensing and the induction of some hypoxic nuclear genes in eukaryotes. In addition, it has been proposed that mitochondrially-generated reactive oxygen and nitrogen species function as signals in a signaling pathway for the induction of hypoxic genes. To gain insight concerning this pathway, we have looked at changes in the functionality of the yeast respiratory chain as cells experience a shift from normoxia to anoxia. These studies have revealed that yeast cells retain the ability to respire at normoxic levels for up to 4 h after a shift and that the mitochondrial cytochrome levels drop rapidly to 30-50% of their normoxic levels and the turnover rate of cytochrome c oxidase (COX) increases during this shift. The increase in COX turnover rate cannot be explained by replacing the aerobic isoform, Va, of cytochrome c oxidase subunit V with the more active hypoxic isoform, Vb. We have also found that mitochondria retain the ability to respire, albeit at reduced levels, in anoxic cells, indicating that yeast cells maintain a functional mitochondrial respiratory chain in the absence of oxygen. This raises the intriguing possibility that the mitochondrial respiratory chain has a previously unexplored role in anoxic cells and may function with an alternative electron acceptor when oxygen is unavailable. (c) 2005 Elsevier B.V. All rights reserved.
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