Heme-copper oxidase subunit I. Heme-copper oxidases are transmembrane protein complexes in the respiratory chains of prokaryotes and mitochondria which catalyze the reduction of O2 and simultaneously pump protons across the membrane. The superfamily is diverse in terms of electron donors, subunit composition, and heme types. The number of subunits varies from three to five in bacteria and up to 13 in mammalian mitochondria. It has been proposed that Archaea acquired heme-copper oxidases through gene transfer from Gram-positive bacteria. Membership in the superfamily is defined by subunit I, which contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme and a copper ion. It also contains a low-spin heme, believed to participate in the transfer of electrons to the binuclear center. Only subunit I is common to the entire superfamily. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from the electron donor on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I of cytochrome c oxidase (CcO) and ubiquinol oxidase. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electron transfer occurs in two segments: from the electron donor to the low-spin heme, and from the low-spin heme to the binuclear center. The first segment can be a multi-step process and varies among the different families, while the second segment, a direct transfer, is consistent throughout the superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:cd01663    72 WLVPLMIGAPDMAFPRLNNLSFWLLPPSLLLLLLSALVEGGAGTGWTVYPPLSSILAHSGPSVDLAIFSLHLAGISSILG 151

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:cd01663   152 AINFITTIFNMRAPGMTLEKMPLFVWSVLITAFLLLLSLPVLAGAITMLLTD 203

Cytochrome C oxidase subunit I. Cytochrome c oxidase (CcO), the terminal oxidase in the respiratory chains of eukaryotes and most bacteria, is a multi-chain transmembrane protein located in the inner membrane of mitochondria and the cell membrane of prokaryotes. It catalyzes the reduction of O2 and simultaneously pumps protons across the membrane. The number of subunits varies from three to five in bacteria and up to 13 in mammalian mitochondria. Only subunits I and II are essential for function, but subunit III, which is also conserved, may play a role in assembly or oxygen delivery to the active site. Subunits I, II, and III of mammalian CcO are encoded within the mitochondrial genome and the remaining 10 subunits are encoded within the nuclear genome. Subunit I contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme (heme a3) and a copper ion (CuB). It also contains a low-spin heme (heme a), believed to participate in the transfer of electrons to the binuclear center. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from cytochrome c on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electrons are transferred from cytochrome c (the electron donor) to heme a via the CuA binuclear site in subunit II, and directly from heme a to the binuclear center.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:cd01663    72 WLVPLMIGAPDMAFPRLNNLSFWLLPPSLLLLLLSALVEGGAGTGWTVYPPLSSILAHSGPSVDLAIFSLHLAGISSILG 151

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:cd01663   152 AINFITTIFNMRAPGMTLEKMPLFVWSVLITAFLLLLSLPVLAGAITMLLTD 203

Heme/copper-type cytochrome/quinol oxidase, subunit 1 [Energy production and conversion];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:COG0843    83 YLVPLQIGARDMAFPRLNALSFWLYLFGGLLLLISLFVGGAADVGWTFYPPLSGLEASPGVGVDLWLLGLALFGVGSILG 162

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:COG0843   163 GVNFIVTILKMRAPGMTLMRMPLFTWAALVTSILILLAFPVLAAALLLLLLD 214

cytochrome aa3 quinol oxidase, subunit I; This family (QoxB) encodes subunit I of the aa3-type quinone oxidase, one of several bacterial terminal oxidases. This complex couples oxidation of reduced quinones with the reduction of molecular oxygen to water and the pumping of protons to form a proton gradient utilized for ATP production. aa3-type oxidases contain two heme a cofactors as well as copper atoms in the active site. [Energy metabolism, Electron transport]

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:TIGR02882 118 IVVPLQIGARDVAFPVLNALSFWLFFAGAMLFNISFVIGGSPDAGWTNYAPLAGPEFSPGVGVNYYLIALQISGIGTLMT 197

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:TIGR02882 198 GINFFVTILKMRAPGMKLMQMPMFTWTTLITTLIIIFAFPVLTVALALMTTD 249

Cytochrome C oxidase subunit I. Cytochrome c oxidase (CcO), the terminal oxidase in the respiratory chains of eukaryotes and most bacteria, is a multi-chain transmembrane protein located in the inner membrane of mitochondria and the cell membrane of prokaryotes. It catalyzes the reduction of O2 and simultaneously pumps protons across the membrane. The number of subunits varies from three to five in bacteria and up to 13 in mammalian mitochondria. Only subunits I and II are essential for function, but subunit III, which is also conserved, may play a role in assembly or oxygen delivery to the active site. Subunits I, II, and III of mammalian CcO are encoded within the mitochondrial genome and the remaining 10 subunits are encoded within the nuclear genome. Subunit I contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme (heme a3) and a copper ion (CuB). It also contains a low-spin heme (heme a), believed to participate in the transfer of electrons to the binuclear center. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from cytochrome c on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electrons are transferred from cytochrome c (the electron donor) to heme a via the CuA binuclear site in subunit II, and directly from heme a to the binuclear center.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:cd01663    72 WLVPLMIGAPDMAFPRLNNLSFWLLPPSLLLLLLSALVEGGAGTGWTVYPPLSSILAHSGPSVDLAIFSLHLAGISSILG 151

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:cd01663   152 AINFITTIFNMRAPGMTLEKMPLFVWSVLITAFLLLLSLPVLAGAITMLLTD 203

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   3 VPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVAAI 82
Cdd:MTH00223   80 VPLMLGAPDMAFPRLNNMSFWLLPPSLYLLLSSSAVESGVGTGWTVYPPLSSNLAHAGPSVDLAIFSLHLAGVSSILGAI 159

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|
gi 1044963311  83 NFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00223  160 NFITTIINMRSPGMQLERLPLFVWSVKVTAFLLLLSLPVLAGAITMLLTD 209

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:MTH00116   81 WLVPLMIGAPDMAFPRMNNMSFWLLPPSFLLLLASSTVEAGAGTGWTVYPPLAGNLAHAGASVDLAIFSLHLAGVSSILG 160

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00116  161 AINFITTCINMKPPAMSQYQTPLFVWSVLITAVLLLLSLPVLAAGITMLLTD 212

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLqSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:MTH00079   82 WMLPLMLGAPDMSFPRLNNLSFWLLPTSLFLILDSCFVDMGPGTSWTVYPPLSTL-GHPGSSVDLAIFSLHCAGISSILG 160

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00079  161 GINFMVTTKNLRSSSISLEHMSLFVWTVFVTVFLLVLSLPVLAGAITMLLTD 212

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:MTH00184   83 WFVPLYIGAPDMAFPRLNNISFWLLPPALTLLLGSAFVEQGAGTGWTVYPPLSSIQAHSGGSVDMAIFSLHLAGISSILG 162

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00184  163 AMNFITTIFNMRAPGITMDRMPLFVWSILVTTFLLLLSLPVLAGAITMLLTD 214

Heme-copper oxidase subunit I. Heme-copper oxidases are transmembrane protein complexes in the respiratory chains of prokaryotes and mitochondria which catalyze the reduction of O2 and simultaneously pump protons across the membrane. The superfamily is diverse in terms of electron donors, subunit composition, and heme types. The number of subunits varies from three to five in bacteria and up to 13 in mammalian mitochondria. It has been proposed that Archaea acquired heme-copper oxidases through gene transfer from Gram-positive bacteria. Membership in the superfamily is defined by subunit I, which contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme and a copper ion. It also contains a low-spin heme, believed to participate in the transfer of electrons to the binuclear center. Only subunit I is common to the entire superfamily. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from the electron donor on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I of cytochrome c oxidase (CcO) and ubiquinol oxidase. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electron transfer occurs in two segments: from the electron donor to the low-spin heme, and from the low-spin heme to the binuclear center. The first segment can be a multi-step process and varies among the different families, while the second segment, a direct transfer, is consistent throughout the superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:cd00919    69 NLLPPLIGARDLAFPRLNNLSFWLFPPGLLLLLSSVLVGGGAGTGWTFYPPLSTLSYSSGVGVDLAILGLHLAGVSSILG 148

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:cd00919   149 AINFITTILNMRAPGMTLDKMPLFVWSVLVTAILLLLALPVLAAALVMLLLD 200

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:MTH00183   81 WLIPLMIGAPDMAFPRMNNMSFWLLPPSFLLLLASSGVEAGAGTGWTVYPPLAGNLAHAGASVDLTIFSLHLAGVSSILG 160

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00183  161 AINFITTIINMKPPAISQYQTPLFVWAVLITAVLLLLSLPVLAAGITMLLTD 212

cytochrome c oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:MTH00037   81 WLIPLMIGAPDMAFPRMNNMSFWLIPPSFLLLLASAGVESGAGTGWTIYPPLSSNIAHAGGSVDLAIFSLHLAGASSILA 160

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:MTH00037  161 SINFITTIINMRTPGMTFDRLPLFVWSVFITAFLLLLSLPVLAGAITMLLTD 212

Heme/copper-type cytochrome/quinol oxidase, subunit 1 [Energy production and conversion];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVA 80
Cdd:COG0843    83 YLVPLQIGARDMAFPRLNALSFWLYLFGGLLLLISLFVGGAADVGWTFYPPLSGLEASPGVGVDLWLLGLALFGVGSILG 162

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1044963311  81 AINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:COG0843   163 GVNFIVTILKMRAPGMTLMRMPLFTWAALVTSILILLAFPVLAAALLLLLLD 214

Ubiquinol oxidase subunit I. Ubiquinol oxidase, the terminal oxidase in the respiratory chains of aerobic bacteria, is a multi-chain transmembrane protein located in the cell membrane. It catalyzes the reduction of O2 and simultaneously pumps protons across the membrane. The number of subunits in ubiquinol oxidase varies from two to five. Subunit I contains a heme-copper binuclear center (the active site where O2 is reduced to water) formed by a high-spin heme and a copper ion. It also contains a low-spin heme, believed to participate in the transfer of electrons from ubiquinol to the binuclear center. For every reduction of an O2 molecule, eight protons are taken from the inside aqueous compartment and four electrons are taken from ubiquinol on the opposite side of the membrane. The four electrons and four of the protons are used in the reduction of O2; the four remaining protons are pumped across the membrane. This charge separation of four charges contributes to the electrochemical gradient used for ATP synthesis. Two proton channels, the D-pathway and K-pathway, leading to the binuclear center have been identified in subunit I. It is generally believed that the channels contain water molecules that act as 'proton wires' to transfer the protons. A well-defined pathway for the transfer of pumped protons beyond the binuclear center has not been identified. Electrons are believed to be transferred directly from ubiquinol (the electron donor) to the low-spin heme, and directly from the low-spin heme to the binuclear center.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   1 YFVPILIGAPDMSFPRLNNFSFWL-LPGAIFLaVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIV 79
Cdd:cd01662    75 YLVPLQIGARDVAFPRLNALSFWLfLFGGLLL-NASLLIGGFPDAGWFAYPPLSGLEYSPGVGVDYWILGLQFSGIGTLL 153

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1044963311  80 AAINFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:cd01662   154 GAINFIVTILKMRAPGMTLMRMPIFTWTTLVTSILILFAFPVLTAALALLELD 206

cytochrome o ubiquinol oxidase subunit I; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1044963311   3 VPILIGAPDMSFPRLNNFSFWLLPGAIFLAVLSTYSEGGPGTGWTVYPPLSSLQSHSGASVDLMIFSFHLVGIGSIVAAI 82
Cdd:PRK15017  127 VPLQIGARDVAFPFLNNLSFWFTVVGVILVNVSLGVGEFAQTGWLAYPPLSGIEYSPGVGVDYWIWSLQLSGIGTTLTGI 206

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|
gi 1044963311  83 NFICTIFYYKNEAMFNKDLPLFVRSVAVTSFLVIVAIPVLAAAITSLLFD 132
Cdd:PRK15017  207 NFFVTILKMRAPGMTMFKMPVFTWASLCANVLIIASFPILTVTVALLTLD 256