Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity
Cytochrome <i>c</i> oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However,...
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MDPI AG
2020-02-01
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| Series: | Cells |
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| Online Access: | https://www.mdpi.com/2073-4409/9/2/443 |
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| author | David Pajuelo Reguera Kristýna Čunátová Marek Vrbacký Alena Pecinová Josef Houštěk Tomáš Mráček Petr Pecina |
| author_facet | David Pajuelo Reguera Kristýna Čunátová Marek Vrbacký Alena Pecinová Josef Houštěk Tomáš Mráček Petr Pecina |
| author_sort | David Pajuelo Reguera |
| collection | DOAJ |
| description | Cytochrome <i>c</i> oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome <i>c</i> affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p<sub>50</sub> (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism. |
| first_indexed | 2024-03-12T07:28:06Z |
| format | Article |
| id | doaj.art-54b8a4f3127f473086215f9b4fa599c2 |
| institution | Directory Open Access Journal |
| issn | 2073-4409 |
| language | English |
| last_indexed | 2024-03-12T07:28:06Z |
| publishDate | 2020-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Cells |
| spelling | doaj.art-54b8a4f3127f473086215f9b4fa599c22023-09-02T21:59:47ZengMDPI AGCells2073-44092020-02-019244310.3390/cells9020443cells9020443Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen AffinityDavid Pajuelo Reguera0Kristýna Čunátová1Marek Vrbacký2Alena Pecinová3Josef Houštěk4Tomáš Mráček5Petr Pecina6Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicDepartment of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech RepublicCytochrome <i>c</i> oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome <i>c</i> affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p<sub>50</sub> (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.https://www.mdpi.com/2073-4409/9/2/443mitochondriaoxphosrespiratory chaincytochrome <i>c</i> oxidasecoxcox4 isoformscox4i2oxygen affinityp<sub>50</sub>oxygen sensing |
| spellingShingle | David Pajuelo Reguera Kristýna Čunátová Marek Vrbacký Alena Pecinová Josef Houštěk Tomáš Mráček Petr Pecina Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity Cells mitochondria oxphos respiratory chain cytochrome <i>c</i> oxidase cox cox4 isoforms cox4i2 oxygen affinity p<sub>50</sub> oxygen sensing |
| title | Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity |
| title_full | Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity |
| title_fullStr | Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity |
| title_full_unstemmed | Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity |
| title_short | Cytochrome <i>c</i> Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity |
| title_sort | cytochrome i c i oxidase subunit 4 isoform exchange results in modulation of oxygen affinity |
| topic | mitochondria oxphos respiratory chain cytochrome <i>c</i> oxidase cox cox4 isoforms cox4i2 oxygen affinity p<sub>50</sub> oxygen sensing |
| url | https://www.mdpi.com/2073-4409/9/2/443 |
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