Assembly factors monitor sequential hemylation of cytochrome <i>b</i> to regulate mitochondrial translation

Hildenbeutel, Markus; Hegg, Eric L.; Stephan, Katharina; Gruschke, Steffi; Meunier, Brigitte; Ott, Martin

doi:10.1083/jcb.201401009

Cited by 67 publications

(107 citation statements)

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“…To test this, Cytb synthesis of the same mutants was analyzed in a third yeast strain, BY4742. In these BY4742 mutants, Cytb labeling dramatically decreased in the absence of Cbp3 and Cbp6, as previously reported for W303 nuclear background (7,14,15) ( Fig. 1B).…”

Section: Complex Activity In D273-10b Lab Strainssupporting

confidence: 88%

“…To see whether assembly defects in bc 1 complex affect Cytb synthesis, we created ⌬qcr7, ⌬cbp4, ⌬cbp3, and ⌬cbp6 mutants in the D273-10b yeast strain. These proteins form the first intermediates at early stages of Cytb assembly and maturation (7,15). To follow mitochondrial translation, the cells were incubated with [ 35 S]methionine in the presence of cycloheximide, and mitochondrial products were analyzed by SDS-PAGE and autoradiography.…”

Section: Complex Activity In D273-10b Lab Strainsmentioning

confidence: 99%

“…Cbp3 and Cbp6 interact with newly synthetized Cytb, probably immediately as the peptide exits the mitochondrial ribosome. This interaction is important for addition of heme b L to Cytb, and it is preserved until Qcr7, Qcr8, the chaperone Cbp4, and the heme b H assemble with Cytb (15). The model suggests that once Cbp3-Cbp6 dissociate from the newly synthesized Cytb, these chaperones are able to activate additional rounds of COB mRNA translation.…”

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confidence: 99%

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Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

García-Guerrero

Camacho‐Villasana

Zamudio-Ochoa

et al. 2018

Journal of Biological Chemistry

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Cytochrome (Cyt) is the only mitochondrial encoded subunit from the complex. Cbp3 and Cbp6 are chaperones necessary for translation of the mRNA and Cyt hemylation. Here we demonstrate that their role in translation is dispensable in some laboratory strains, whereas their role in Cyt hemylation seems to be universally conserved. BY4742 yeast requires Cbp3 and Cbp6 for efficient mRNA translation, whereas the D273-10b strain synthesizes Cyt at wildtype levels in the absence of Cbp3 and Cbp6. Steady-state levels of Cyt are close to wildtype in mutant D273-10b cells, and Cyt forms non-functional, supercomplex-like species with cytochrome oxidase, in which at least core 1, cytochrome, and Rieske iron-sulfur subunits are present. We demonstrated that Cbp3 interacts with the mitochondrial ribosome and with the mRNA in both BY4742 and D273-10b strains. The polymorphism(s) causing the differential function of Cbp3, Cbp6, and the assembly feedback regulation of Cyt synthesis is of nuclear origin rather than mitochondrial, and Smt1, a mRNA-binding protein, does not seem to be involved in the observed differential phenotype. Our results indicate that the essential role of Cbp3 and Cbp6 is to assist Cyt hemylation and demonstrate that in the absence of heme , Cyt can form non-functional supercomplexes with cytochrome oxidase. Our observations support that an additional protein or proteins are involved in Cyt synthesis in some yeast strains.

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Section: Complex Activity In D273-10b Lab Strainssupporting

confidence: 88%

Section: Complex Activity In D273-10b Lab Strainsmentioning

confidence: 99%

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confidence: 99%

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Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

García-Guerrero

Camacho‐Villasana

Zamudio-Ochoa

et al. 2018

Journal of Biological Chemistry

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“…Most antibodies used in this study were generated by our laboratory or in the laboratories of J. Schatz (University of Basel, Basel, Switzerland) or C. Koehler (UCLA) and have been described previously 3, 63, 65, 67-69 . Other antibodies used were mouse anti-Sec62p (kind gift of Dr. David Meyers (UCLA)), mouse anti-FLAG (clone M2, Sigma), mouse anti-Dpm1p (113686, Abcam), rabbit anti-Qcr7p 70 , rabbit antisera reactive to Coq1p 71 , Coq4p 72 , Coq7p 73 , or Coq9p 74 , rabbit antisera raised against the C-terminus of Cho1p 34 , rabbit anti-Kar2p 36 and horseradish peroxidase-conjugated (Thermo Fisher Scientific) or IRDye 800CW (LI-COR) secondary antibodies.…”

Section: Methodsmentioning

confidence: 99%

Phosphatidylethanolamine made in the inner mitochondrial membrane is essential for yeast cytochromebc₁complex function

Calzada

Claypool

2018

Preprint

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Of the four separate PE biosynthetic pathways in eukaryotes, one occurs in the mitochondrial inner membrane (IM) and is executed by phosphatidylserine decarboxylase (Psd1p). Deletion of Psd1, which is lethal in mice, compromises mitochondrial function. We hypothesize that this reflects inefficient import of non-mitochondrial PE into the IM. To test this, we re-wired PE metabolism in yeast by re-directing Psd1p to the outer mitochondrial membrane or the endomembrane system. Our biochemical and functional analyses identified the IMS as the greatest barrier for PE import and demonstrated that PE synthesis in the IM is critical for cytochrome bc1 complex (III) function. Importantly, mutations predicted to disrupt a conserved PE-binding site in the complex III subunit, Qcr7p, impaired complex III activity similar to PSD1 deletion. Collectively, these data demonstrate that PE made in the IM by Psd1p is critical to support the intrinsic functionality of complex III and establish one likely mechanism.

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“…CIII assembly starts with the synthesis of cytochrome b by dedicated ribosomes, where the yeast translation factors Cbp3 (mammalian UQCC1) and Cbp6 (UQCC2) are bound to the peptide exit tunnel and direct the nascent polypeptide to translocate into the mitochondrial inner membrane [12,13]. A third factor, Cbp4 (UQCC3), is bound to cytochrome b after the b L heme but before the b H heme are incorporated into the apoprotein [14]. Pathological mutations associated with human cIII deficiency have been described in UQCC2 [15] and UQCC3 [16].…”

Section: Mammalian Complex III Assembly Processmentioning

confidence: 99%

Mitochondrial complex III Rieske Fe-S protein processing and assembly

Fernández-Vizarra

Zeviani

2018

Cell Cycle

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Regulation of the mitochondrial respiratory chain biogenesis is a matter of great interest because of its implications for mitochondrial disease. One of the mitochondrial disease genes recently discovered associated to encephalopathy and mitochondrial complex III (cIII) deficiency is TTC19. Our study of TTC19-deficient human and mouse models, has led us to propose a post-assembly quality control role or 'husbandry' function for this factor that is linked to Rieske Fe-S protein (UQCRFS1). UQCRFS1 is the last incorporated cIII subunit, and its presence is essential for enzymatic activity. During UQCRFS1 assembly, the precursor is cleaved and its N-terminal part remains bound to the complex, between the two core subunits (UQCRC1 and UQCRC2). In the absence of TTC19 there is a prominent accumulation of these UQCRFS1-derived N-terminal fragments that proved to be detrimental for cIII function. In this article we will discuss some ideas around the UQCRFS1 processing and assembly and its importance for the regulation of cIII activity and biogenesis.

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Assembly factors monitor sequential hemylation of cytochrome b to regulate mitochondrial translation

Abstract: Assembly of the two heme b cofactors into the respiratory chain complex III subunit cytochrome b occurs in a step-by-step process that is monitored by assembly factors and regulates additional cytochrome b synthesis through a feedback loop.

Cited by 67 publications

References 41 publications

Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

Phosphatidylethanolamine made in the inner mitochondrial membrane is essential for yeast cytochromebc₁complex function

Mitochondrial complex III Rieske Fe-S protein processing and assembly

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Assembly factors monitor sequential hemylation of cytochrome b to regulate mitochondrial translation

Abstract: Assembly of the two heme b cofactors into the respiratory chain complex III subunit cytochrome b occurs in a step-by-step process that is monitored by assembly factors and regulates additional cytochrome b synthesis through a feedback loop.

Cited by 67 publications

References 41 publications

Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

Cbp3 and Cbp6 are dispensable for synthesis regulation of cytochrome b in yeast mitochondria

Phosphatidylethanolamine made in the inner mitochondrial membrane is essential for yeast cytochromebc1complex function

Mitochondrial complex III Rieske Fe-S protein processing and assembly

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Phosphatidylethanolamine made in the inner mitochondrial membrane is essential for yeast cytochromebc₁complex function