Structure and expression of complex I in plant mitochondria

RNA splicing is an essential post-transcriptional regulation in plant mitochondria and chloroplasts. As the mechanism of RNA splicing remains obscure, identification and functional elucidation of new splicing factors are necessary. Through a characterization of two maize mutants, we cloned Empty pericarp 24 (Emp24) and Empty pericarp 25 (Emp25). Both Emp24 and Emp25 encode mitochondrion-targeted P-type PPR proteins. EMP24 is required for the splicing of nad4 introns 1 and 3, which was reported (Ren Z. et al., 2019), and EMP25 functions in the splicing of nad5 introns 1, 2, and 3. Absence of either Nad4 or Nad5 proteins blocks the assembly of mitochondrial complex I, resulting in the formation of a sub-sized complex I of similar size in both mutants. Mass spectrometry identification revealed that the subcomplexes in both mutants lack an identical set of proteins of complex I. These results indicate that EMP24 and EMP25 function in the splicing of nad4 and nad5 introns, respectively, and are essential to maize kernel development. The identification of the subcomplexes provides genetic and molecular insights into the modular complex I assembly pathway in maize.

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Oxidation and reduction of pyridine nucleotides in alamethicin-permeabilized plant mitochondria

Biochemical Journal ◽

10.1042/bj20031969 ◽

2004 ◽

Vol 380 (1) ◽

pp. 193-202 ◽

Cited By ~ 29

Author(s):

Fredrik I. JOHANSSON ◽

Agnieszka M. MICHALECKA ◽

Ian M. MØLLER ◽

Allan G. RASMUSSON

Keyword(s):

Electron Transport ◽

Complex I ◽

Electron Transport Chain ◽

Nadh Dehydrogenase ◽

Plant Mitochondria ◽

Inner Mitochondrial Membrane ◽

Intact Cells ◽

Transport Chain ◽

Invasive Method

The inner mitochondrial membrane is selectively permeable, which limits the transport of solutes and metabolites across the membrane. This constitutes a problem when intramitochondrial enzymes are studied. The channel-forming antibiotic AlaM (alamethicin) was used as a potentially less invasive method to permeabilize mitochondria and study the highly branched electron-transport chain in potato tuber (Solanum tuberosum) and pea leaf (Pisum sativum) mitochondria. We show that AlaM permeabilized the inner membrane of plant mitochondria to NAD(P)H, allowing the quantification of internal NAD(P)H dehydrogenases as well as matrix enzymes in situ. AlaM was found to inhibit the electron-transport chain at the external Ca2+-dependent rotenone-insensitive NADH dehydrogenase and around complexes III and IV. Nevertheless, under optimal conditions, especially complex I-mediated NADH oxidation in AlaM-treated mitochondria was much higher than what has been previously measured by other techniques. Our results also show a difference in substrate specificities for complex I in mitochondria as compared with inside-out submitochondrial particles. AlaM facilitated the passage of cofactors to and from the mitochondrial matrix and allowed the determination of NAD+ requirements of malate oxidation in situ. In summary, we conclude that AlaM provides the best method for quantifying NADH dehydrogenase activities and that AlaM will prove to be an important method to study enzymes under conditions that resemble their native environment not only in plant mitochondria but also in other membrane-enclosed compartments, such as intact cells, chloroplasts and peroxisomes.

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The kinetics of NADH oxidation by complex I of isolated plant mitochondria

Physiologia Plantarum ◽

10.1034/j.1399-3054.1990.800112.x ◽

1990 ◽

Vol 80 (1) ◽

pp. 75-82 ◽

Cited By ~ 21

Author(s):

Kathleen L. Soole ◽

Ian B. Dry ◽

Alan T. James ◽

Joseph T. Wiskich

Keyword(s):

Complex I ◽

Plant Mitochondria ◽

Nadh Oxidation ◽

Kinetics Of

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Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates

FEBS Letters ◽

10.1016/s0014-5793(99)00616-x ◽

1999 ◽

Vol 451 (3) ◽

pp. 347-350 ◽

Cited By ~ 51

Author(s):

Enrico Braidot ◽

Elisa Petrussa ◽

Angelo Vianello ◽

Francesco Macrı̀

Keyword(s):

Hydrogen Peroxide ◽

Complex I ◽

Plant Mitochondria ◽

Higher Plant ◽

Complex Ii ◽

Hydrogen Peroxide Generation

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Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner

Biochemical Journal ◽

10.1042/bj20120396 ◽

2012 ◽

Vol 449 (1) ◽

pp. 263-273 ◽

Cited By ~ 13

Author(s):

Vagner Simonin ◽

Antonio Galina

Keyword(s):

Nitric Oxide ◽

Oxygen Consumption ◽

Potato Tuber ◽

Succinate Dehydrogenase ◽

Mitochondrial Respiration ◽

Complex I ◽

Nadh Dehydrogenase ◽

Electron Flow ◽

Plant Mitochondria ◽

Deta Nonoate

NO (nitric oxide) is described as an inhibitor of plant and mammalian respiratory chains owing to its high affinity for COX (cytochrome c oxidase), which hinders the reduction of oxygen to water. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well. We analysed oxygen consumption supported by complex I and/or complex II and/or external NADH dehydrogenase in Percoll-isolated potato tuber (Solanum tuberosum) mitochondria. When mitochondrial respiration was stimulated by succinate, adding the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) or DETA-NONOate caused a 70% reduction in oxygen consumption rate in state 3 (stimulated with 1 mM of ADP). This inhibition was followed by a significant increase in the Km value of SDH (succinate dehydrogenase) for succinate (Km of 0.77±0.19 to 34.3±5.9 mM, in the presence of NO). When mitochondrial respiration was stimulated by external NADH dehydrogenase or complex I, NO had no effect on respiration. NO itself and DETA-NONOate had similar effects to SNAP. No significant inhibition of respiration was observed in the absence of ADP. More importantly, SNAP inhibited PTM (potato tuber mitochondria) respiration independently of oxygen tensions, indicating a different kinetic mechanism from that observed in mammalian mitochondria. We also observed, in an FAD reduction assay, that SNAP blocked the intrinsic SDH electron flow in much the same way as TTFA (thenoyltrifluoroacetone), a non-competitive SDH inhibitor. We suggest that NO inhibits SDH in its ubiquinone site or its Fe–S centres. These data indicate that SDH has an alternative site of NO action in plant mitochondria.

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The kinetics of NADH oxidation by complex I of isolated plant mitochondria

Physiologia Plantarum ◽

10.1111/j.1399-3054.1990.tb04377.x ◽

1990 ◽

Vol 80 (1) ◽

pp. 75-82

Author(s):

Kathleen L. Sooie ◽

Ian B. Dry ◽

Alan T. James ◽

Joseph T. Wiskich

Keyword(s):

Complex I ◽

Plant Mitochondria ◽

Nadh Oxidation ◽

Kinetics Of

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The PPR-related splicing cofactor MSP1/EMB1025 protein, encoded by At4g20090, encode an essential protein that is required for the splicing of nad1 intron 1 and for the biogenesis of complex I in Arabidopsis mitochondria

10.1101/615856 ◽

2019 ◽

Author(s):

Corinne Best ◽

Michal Zmudjak ◽

Oren Ostersetzer-Biran

Keyword(s):

Complex I ◽

Rna Binding ◽

Embryo Rescue ◽

Plant Mitochondria ◽

Rna Stability ◽

Pentatricopeptide Repeat ◽

Ppr Protein ◽

Intron 1 ◽

Rna Maturation ◽

Embryonic Arrest

AbstractGroup II introns are particularly plentiful within plant mitochondrial genomes (mtDNAs), where they interrupt the coding-regions of many organellar genes, especialy within complex I (CI) subunits. Their splicing is essential for the biogenesis of the respiratory system and is facilitated by various protein-cofactors that belong to a diverse set of RNA-binding cofactors. These including maturases, which co-evolved with their host-introns, and various trans-acting factors, such as members of the pentatricopeptide-repeat (PPR) protein family. The genomes of angiosperms contain hundreds of PPR-related genes that are postulated to reside within the organelles and affect diverse posttranscriptional steps, such as editing, RNA-stability and processing or translation. Here, we report the characterization of MSP1 (Mitochondria Splicing PPR-factor 1; also denoted as EMB1025), which plays a key role in the processing of nad1 pre-RNAs in Arabidopsis mitochondria. Mutations in MSP1 gene-locus (At4g20090) result in early embryonic arrest. To analyze the putative roles of MSP1 in organellar RNA-metabolism we used a modified embryo-rescue method, which allowed us to obtain sufficient plant tissue for the analysis of the RNA and protein profiles associated with msp1 mutants. Our data indicate that MSP1 is essential for the trans-splicing of nad1 intron 1 in Arabidopsis mitochondria. Accordingly, msp1 mutants show CI biogenesis defects and reduced respiratory-mediated functions. These results provide with important insights into the roles of nuclear-encoded factors during early plant development, and contribute to our limited understanding of the importance of RNA-maturation and splicing in plant mitochondria during early embryogenesis.

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