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PDBsum entry 6t0b
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Oxidoreductase
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PDB id
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6t0b
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Contents |
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431 a.a.
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352 a.a.
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385 a.a.
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247 a.a.
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185 a.a.
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75 a.a.
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126 a.a.
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93 a.a.
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57 a.a.
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76 a.a.
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534 a.a.
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236 a.a.
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269 a.a.
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120 a.a.
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133 a.a.
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102 a.a.
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59 a.a.
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51 a.a.
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55 a.a.
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75 a.a.
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113 a.a.
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45 a.a.
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99 a.a.
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 _ZN
×2
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 _CU
×2
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 _CA
×2
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 _MG
×2
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References listed in PDB file
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Key reference
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Title
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Rcf2 revealed in cryo-Em structures of hypoxic isoforms of mature mitochondrial III-Iv supercomplexes.
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Authors
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A.M.Hartley,
B.Meunier,
N.Pinotsis,
A.Maréchal.
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Ref.
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Proc Natl Acad Sci U S A, 2020,
117,
9329-9337.
[DOI no: ]
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PubMed id
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Abstract
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The organization of the mitochondrial electron transport chain proteins into
supercomplexes (SCs) is now undisputed; however, their assembly process, or the
role of differential expression isoforms, remain to be determined. In
Saccharomyces cerevisiae, cytochrome c oxidase (CIV) forms SCs of
varying stoichiometry with cytochrome bc1 (CIII). Recent
studies have revealed, in normoxic growth conditions, an interface made
exclusively by Cox5A, the only yeast respiratory protein that exists as one of
two isoforms depending on oxygen levels. Here we present the cryo-EM structures
of the III2-IV1 and III2-IV2 SCs
containing the hypoxic isoform Cox5B solved at 3.4 and 2.8 Å, respectively. We
show that the change of isoform does not affect SC formation or activity, and
that SC stoichiometry is dictated by the level of CIII/CIV biosynthesis.
Comparison of the CIV5B- and CIV5A-containing SC
structures highlighted few differences, found mainly in the region of Cox5.
Additional density was revealed in all SCs, independent of the CIV isoform, in a
pocket formed by Cox1, Cox3, Cox12, and Cox13, away from the CIII-CIV interface.
In the CIV5B-containing hypoxic SCs, this could be confidently
assigned to the hypoxia-induced gene 1 (Hig1) type 2 protein Rcf2. With
conserved residues in mammalian Hig1 proteins and Cox3/Cox12/Cox13 orthologs, we
propose that Hig1 type 2 proteins are stoichiometric subunits of CIV, at least
when within a III-IV SC.
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