scholarly journals Inverse regulation of the yeast COX5 genes by oxygen and heme.

1989 ◽  
Vol 9 (5) ◽  
pp. 1958-1964 ◽  
Author(s):  
M R Hodge ◽  
G Kim ◽  
K Singh ◽  
M G Cumsky
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Environmental Conditions ◽  
Physiological Response ◽  
Biosynthetic Pathway ◽  
Yeast Cells ◽  
Yeast Mitochondria ◽  
Aerobic Growth ◽  
Yeast Strains ◽  
Yeast Genes

The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.

Inverse regulation of the yeast COX5 genes by oxygen and heme

1989 ◽  
Vol 9 (5) ◽  
pp. 1958-1964
Author(s):  
M R Hodge ◽  
G Kim ◽  
K Singh ◽  
M G Cumsky
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Environmental Conditions ◽  
Physiological Response ◽  
Biosynthetic Pathway ◽  
Yeast Cells ◽  
Yeast Mitochondria ◽  
Aerobic Growth ◽  
Yeast Strains ◽  
Yeast Genes

The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.

scholarly journals Coa2 Is an Assembly Factor for Yeast Cytochrome c Oxidase Biogenesis That Facilitates the Maturation of Cox1

2008 ◽  
Vol 28 (16) ◽  
pp. 4927-4939 ◽  
Author(s):  
Fabien Pierrel ◽  
Oleh Khalimonchuk ◽  
Paul A. Cobine ◽  
Megan Bestwick ◽  
Dennis R. Winge
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Proteolytic Activity ◽  
Yeast Mitochondria ◽  
Early Step ◽  
Rapid Degradation ◽  
Respiratory Deficiency ◽  
The Matrix ◽  
Assembly Factor

ABSTRACT The assembly of cytochrome c oxidase (CcO) in yeast mitochondria is dependent on a new assembly factor designated Coa2. Coa2 was identified from its ability to suppress the respiratory deficiency of coa1Δ and shy1Δ cells. Coa1 and Shy1 function at an early step in maturation of the Cox1 subunit of CcO. Coa2 functions downstream of the Mss51-Coa1 step in Cox1 maturation and likely concurrent with the Shy1-related heme a 3 insertion into Cox1. Coa2 interacts with Shy1. Cells lacking Coa2 show a rapid degradation of newly synthesized Cox1. Rapid Cox1 proteolysis also occurs in shy1Δ cells, suggesting that in the absence of Coa2 or Shy1, Cox1 forms an unstable conformer. Overexpression of Cox10 or Cox5a and Cox6 or attenuation of the proteolytic activity of the m-AAA protease partially restores respiration in coa2Δ cells. The matrix-localized Coa2 protein may aid in stabilizing an early Cox1 intermediate containing the nuclear subunits Cox5a and Cox6.

scholarly journals Coenzyme Q10 deficiencies: pathways in yeast and humans

2018 ◽  
Vol 62 (3) ◽  
pp. 361-376 ◽  
Author(s):  
Agape M. Awad ◽  
Michelle C. Bradley ◽  
Lucía Fernández-del-Río ◽  
Anish Nag ◽  
Hui S. Tsui ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
De Novo ◽  
Human Gene ◽  
Coenzyme Q ◽  
Human Cells ◽  
Yeast Cells ◽  
Gene Products ◽  
Functional Conservation ◽  
Hydrophobic Lipid ◽  
Yeast Genes

Coenzyme Q (ubiquinone or CoQ) is an essential lipid that plays a role in mitochondrial respiratory electron transport and serves as an important antioxidant. In human and yeast cells, CoQ synthesis derives from aromatic ring precursors and the isoprene biosynthetic pathway. Saccharomyces cerevisiae coq mutants provide a powerful model for our understanding of CoQ biosynthesis. This review focusses on the biosynthesis of CoQ in yeast and the relevance of this model to CoQ biosynthesis in human cells. The COQ1–COQ11 yeast genes are required for efficient biosynthesis of yeast CoQ. Expression of human homologs of yeast COQ1–COQ10 genes restore CoQ biosynthesis in the corresponding yeast coq mutants, indicating profound functional conservation. Thus, yeast provides a simple yet effective model to investigate and define the function and possible pathology of human COQ (yeast or human gene involved in CoQ biosynthesis) gene polymorphisms and mutations. Biosynthesis of CoQ in yeast and human cells depends on high molecular mass multisubunit complexes consisting of several of the COQ gene products, as well as CoQ itself and CoQ intermediates. The CoQ synthome in yeast or Complex Q in human cells, is essential for de novo biosynthesis of CoQ. Although some human CoQ deficiencies respond to dietary supplementation with CoQ, in general the uptake and assimilation of this very hydrophobic lipid is inefficient. Simple natural products may serve as alternate ring precursors in CoQ biosynthesis in both yeast and human cells, and these compounds may act to enhance biosynthesis of CoQ or may bypass certain deficient steps in the CoQ biosynthetic pathway.

Neither respiration nor cytochrome c oxidase affects mitochondrial morphology in Saccharomyces cerevisiae.

1998 ◽  
Vol 201 (11) ◽  
pp. 1729-1737 ◽  
Author(s):  
C Church ◽  
R O Poyton
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Respiratory Chain ◽  
Glucose Repression ◽  
Nuclear Gene ◽  
Yeast Cells ◽  
Mitochondrial Proteins ◽  
Mitochondrial Morphology ◽  
Per Se ◽  
Mitochondrial Reticulum

Previous studies have reported that mitochondrial morphology and volume in yeast cells are linked to cellular respiratory capacity. These studies revealed that mitochondrial morphology in glucose-repressed or anaerobically grown cells, which lack or have reduced levels of respiration, is different from that in fully respiring cells. Although both oxygen deprivation and glucose repression decrease the levels of respiratory chain proteins, they decrease the expression of many non-mitochondrial proteins as well, making it difficult to determine whether it is a defect in respiration or something else that effects mitochondrial morphology. To determine whether mitochondrial morphology is dependent on respiration per se, we used a strain with a null mutation in PET100, a nuclear gene that is specifically required for the assembly of cytochrome c oxidase. Although this strain lacks respiration, the mitochondrial morphology and volumes are both comparable to those found in its respiration-proficient parent. These findings indicate that respiration is not involved in the establishment or maintenance of yeast mitochondrial morphology, and that the previously observed effects of oxygen availability and glucose repression on mitochondrial morphology are not exerted through the respiratory chain. By applying the principle of symmorphosis to these findings, we conclude that the shape and size of the mitochondrial reticulum found in respiring yeast cells is maintained for reasons other than respiration.

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