| 1. |
- Belt, Katharina, et al.
(författare)
-
An assembly factor promotes assembly of flavinated SDH1 into the succinate dehydrogenase complex
- 2018
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 177:4, s. 1439-1452
-
Tidskriftsartikel (refereegranskat)abstract
- Succinate dehydrogenase (Complex II; SDH) plays an important role in mitochondrial respiratory metabolism. The SDH complex consists of four core subunits and multiple cofactors, which must be assembled correctly to ensure enzyme function. To date, only an assembly factor (SDHAF2) required for FAD insertion into subunit SDH1 has been identified in plants. Here, we report the identification of Arabidopsis (Arabidopsis thaliana) At5g67490 as a second SDH assembly factor. Knockout of At5g67490 (sdhaf4) did not cause any phenotypic variation in seedlings but resulted in a decrease in both SDH activity and the succinate-dependent respiration rate as well as increased accumulation of succinate. Mass spectrometry analyses revealed stable levels of FAD-SDH1 in sdhaf4, together with increased levels of the FAD-SDH1 assembly factor, SDHAF2, and reduced levels of SDH2 compared with the wild type. Loss of SDHAF4 in sdhaf4 inhibited the formation of the SDH1/SDH2 intermediate, leading to the accumulation of soluble SDH1 in the mitochondrial matrix and reduced levels of SDH1 in the membrane. The increased levels of SDHAF2 suggest that the stabilization of soluble FAD-SDH1 depends on SDHAF2 availability. We conclude that SDHAF4 acts on FAD-SDH1 and promotes its assembly with SDH2, thereby stabilizing SDH2 and enabling its full assembly with SDH3/ SDH4 to form the SDH complex.
|
|
| 2. |
- Ivanova, Aneta, et al.
(författare)
-
A Mitochondrial LYR Protein Is Required for Complex I Assembly
- 2019
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 181:4, s. 1632-1650
-
Tidskriftsartikel (refereegranskat)abstract
- Complex I biogenesis requires the expression of both nuclear and mitochondrial genes, the import of proteins, cofactor biosynthesis, and the assembly of at least 49 individual subunits. Assembly factors interact with subunits of Complex I but are not part of the final holocomplex. We show that in Arabidopsis (Arabidopsis thaliana), a mitochondrial matrix protein (EMB1793, At1g76060), which we term COMPLEX I ASSEMBLY FACTOR 1 (CIAF1), contains a LYR domain and is required for Complex I assembly. T-DNA insertion mutants of CIAF1 lack Complex I and the Supercomplex I+III. Biochemical characterization shows that the assembly of Complex I is stalled at 650 and 800 kD intermediates in mitochondria isolated from ciaf1 mutant lines.I. Yeast-two-hybrid interaction and complementation assays indicate that CIAF1 specifically interacts with the 23-kD TYKY-1 matrix domain subunit of Complex I and likely plays a role in Fe-S insertion into this subunit. These data show that CIAF1 plays an essential role in assembling the peripheral matrix arm Complex I subunits into the Complex I holoenzyme. A mitochondrial LYR protein is involved in the biogenesis of a matrix arm domain subunit of Complex I.
|
|
| 3. |
- Li, Ying, et al.
(författare)
-
The mitochondrial LYR protein SDHAF1 is required for succinate dehydrogenase activity in Arabidopsis
- 2022
-
Ingår i: Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 110:2, s. 499-512
-
Tidskriftsartikel (refereegranskat)abstract
- Succinate dehydrogenase (SDH, complex II), which plays an essential role in mitochondrial respiration and tricarboxylic acid metabolism, requires the assembly of eight nuclear-encoded subunits and the insertion of various cofactors. Here, we report on the characterization of an Arabidopsis thaliana leucine-tyrosine-arginine (LYR) protein family member SDHAF1, (At2g39725) is a factor required for SDH activity. SDHAF1 is located in mitochondria and can fully complement the yeast SDHAF1 deletion strain. Knockdown of SDHAF1 using RNA interference resulted in a decrease in seedling hypocotyl elongation and reduced SDH activity. Proteomic analyses revealed a decreased abundance of various SDH subunits and assembly factors. Protein interaction assays revealed that SDHAF1 can interact exclusively with the Fe-S cluster-containing subunit SDH2 and HSCB, a cochaperone involved in Fe-S cluster complex recruitment. Therefore, we propose that in Arabidopsis, SDHAF1 plays a role in the biogenesis of SDH2 to form the functional complex II, which is essential for mitochondrial respiration and metabolism.
|
|
| 4. |
- Wang, Yan, et al.
(författare)
-
Inactivation of Mitochondrial Complex I Induces the Expression of a Twin Cysteine Protein that Targets and Affects Cytosolic, Chloroplastidic and Mitochondrial Function
- 2016
-
Ingår i: Molecular Plant. - : Elsevier BV. - 1674-2052 .- 1752-9867. ; 9:5, s. 696-710
-
Tidskriftsartikel (refereegranskat)abstract
- At12Cys-1 (At5g64400) and At12Cys-2 (At5g09570) are two closely related isogenes that encode small, twin cysteine proteins, typically located in mitochondria. At12Cys-2 transcript is induced in a variety of mutants with disrupted mitochondrial proteins, but an increase in At12Cys protein is only detected in mutants with reduced mitochondrial complex I abundance. Induction of At12Cys protein in mutants that lack mitochondrial complex I is accompanied by At12Cys protein located in mitochondria, chloroplasts, and the cytosol. Biochemical analyses revealed that even single gene deletions, i.e., At12cys-1 or At12cys-2, have an effect on mitochondrial and chloroplast functions. However, only double mutants, i.e., At12cys-1: At12cys-2, affect the abundance of protein and mRNA transcripts encoding translation elongation factors as well as rRNA abundance. Blue native PAGE showed that At12Cys co-migrated with mitochondrial supercomplex I + III. Likewise, deletion of both At12cys-1 and At12cys-2 genes, but not single gene deletions, results in enhanced tolerance to drought and light stress and increased anti-oxidant capacity. The induction and multiple localization of At12Cys upon a reduction in complex I abundance provides a mechanism to specifically signal mitochondrial dysfunction to the cytosol and then beyond to other organelles in the cell.
|
|
