Subunit III of cytochrome c oxidase is not involved in proton translocation: a site-directed mutagenesis study.

Haltia, Tuomas; Saraste, Matti; Wikström, Mårten

doi:10.1002/j.1460-2075.1991.tb07731.x

Cited by 109 publications

(54 citation statements)

References 48 publications

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“…2). Subunit III has no prosthetic groups and does not appear to be involved in pumping protons, so its role may be structural (33). An Mg 2ϩ ion is coordinated between elements of subunits I and II and is close to the Cu A site (34).…”

Section: Structure Of the Cytochrome Oxidase Complexmentioning

confidence: 99%

Human Cytochrome Oxidase Deficiency

Robinson

2000

Pediatr Res

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Section: Structure Of the Cytochrome Oxidase Complexmentioning

confidence: 99%

Human Cytochrome Oxidase Deficiency

Robinson

2000

Pediatr Res

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“…5). The first glutamate residue is homologous to the dicyclohexylcarbodiimide-binding residue in subunit I11 of several other oxidases, and the aspartate in the highly conserved C-terminal helix is totally invariant (Saraste, 1990 ;Haltia et al, 1991).…”

Section: Soxm Purifies With Cytochrome B Soxc and A Rieske Fe-s Cementioning

confidence: 99%

“…Subunit I1 in cytochrome c oxidases binds the electron-donating substrate (Taha and FergusonMiller, 1992) and contains a copper site which is missing from the quinol oxidases (Van der Oost et al, 1992). In contrast, subunit I11 has no redox centers, and its functional role is not understood (Haltia et al, 1991). In the SoxABCD complex, SoxB and SoxA are related to the subunits I and I1 of cytochrome oxidase.…”

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confidence: 99%

A Second Terminal Oxidase in Sulfolobus acidocaldarius

Lübben

Arnaud

Castresana

et al. 1994

European Journal of Biochemistry

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We previously found that the soxABCD operon encodes a quinol oxidase complex in Sulfolobus acidocaldarius and this enzyme was purified and characterized. In this study, we have used a cloning procedure based on the conservation of oxidase sequences and the polymerase chain reaction to isolate a new gene (soxM) encoding a subunit of another terminal oxidase. This terminal oxidase is a fusion between two central components of cytochrome oxidases, subunits I and III. soxM forms a transcriptional unit which is expressed under heterotrophic growth conditions. The corresponding protein was detected by direct protein sequencing in a preparation enriched with a cytochrome absorbing light at 562 nm. This preparation contains a terminal oxidase which is able to oxidize the artificial substrate N,N,N′,N′ ‐tetramethyl‐p ‐phenylenediamine. This preparation also contains SoxC, a protein homologous to the mitochondrial cytochrome b, and a Rieske iron‐sulphur center. We suggest that SoxM is the core component of a second terminal oxidase complex and that this complex may share a subunit (SoxC) with the SoxABCD complex.

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“…However, sequence alignment of NorE with subunit III proteins reveals the conservation of a number of residues, in particular the dicyclohexylcarbodiimide (DCCD) binding glu residue found in subunit III, indicating that NorE is structurally or biochemically similar to subunit III, which has been shown to be required for oxidase stability (22,23). Even in the aa 3 oxidase family, the interaction of subunit III with subunit I is relatively weak.…”

Section: Discussionmentioning

confidence: 99%

Role of norEF in Denitrification, Elucidated by Physiological Experiments with Rhodobacter sphaeroides

et al. 2014

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Many denitrifying organisms contain the norEF gene cluster, which codes for two proteins that are thought to be involved in denitrification because they are expressed during the reduction of nitrite and nitric oxide. The products of both genes are predicted to be membrane associated, and the norE product is a member of the cytochrome c oxidase subunit III family. However, the specific role of norEF is unknown. The denitrification phenotypes of Rhodobacter sphaeroides strains with and without norEF genes were studied, and it was found that loss of norEF lowered the rate of denitrification from nitrate and resulted in accumulation of micromolar concentrations of nitric oxide during denitrification from nitrite. norEF appears to have no direct role in the reduction of nitric oxide; however, since deletion of norEF in the wild-type 2.4.3 strain had essentially no influence on the kinetics of potential nitric oxide reduction (V max and K s ), as measured by monitoring the depletion of a bolus of nitric oxide injected into anoxic cultures without any other electron acceptors. However, norEF-deficient cells that had undergone a more chronic exposure to micromolar concentrations of nitric oxide showed an ϳ50% reduction in V max but no change in apparent K s . These results can explain the occurrence of norEF in the 2.4.3 strain of R. sphaeroides, which can reduce nitrate to nitrous oxide, and their absence from strains such as 2.4.1, which likely use nitric oxide reductase to mitigate stress due to episodic exposure to nitric oxide from exogenous sources.

show abstract

Subunit III of cytochrome c oxidase is not involved in proton translocation: a site-directed mutagenesis study.

Cited by 109 publications

References 48 publications

Human Cytochrome Oxidase Deficiency

Human Cytochrome Oxidase Deficiency

A Second Terminal Oxidase in Sulfolobus acidocaldarius

Role of norEF in Denitrification, Elucidated by Physiological Experiments with Rhodobacter sphaeroides

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