Activation of Mitochondrial Protein Phosphatase SLP2 by MIA40 Regulates Seed Germination

Uhrig, R. Glen; Labandera, Anne‐Marie; Tang, Lay-Yin; Sieben, Nicholas A; Goudreault, Marilyn; Yeung, Edward C.; Gingras, Anne‐Claude; Samuel, Marcus A.; Moorhead, Greg B. G.

doi:10.1104/pp.16.01641

Cited by 25 publications

(14 citation statements)

References 49 publications

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“…Similar (low) copy numbers of both the kinase and the phosphatase per mitochondrion may be regarded as further evidence for their function as a regulatory couple. Another phosphatase, SLP2, which is present in the IMS, and involved in the regulation of seed germination (Uhrig et al ., ), was detected at comparably low copy number (296 copies).…”

Section: Resultsmentioning

confidence: 97%

Single organelle function and organization as estimated from Arabidopsis mitochondrial proteomics

et al. 2019

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Summary Mitochondria host vital cellular functions, including oxidative phosphorylation and co‐factor biosynthesis, which are reflected in their proteome. At the cellular level plant mitochondria are organized into hundreds of discrete functional entities, which undergo dynamic fission and fusion. It is the individual organelle that operates in the living cell, yet biochemical and physiological assessments have exclusively focused on the characteristics of large populations of mitochondria. Here, we explore the protein composition of an individual average plant mitochondrion to deduce principles of functional and structural organisation. We perform proteomics on purified mitochondria from cultured heterotrophic Arabidopsis cells with intensity‐based absolute quantification and scale the dataset to the single organelle based on criteria that are justified by experimental evidence and theoretical considerations. We estimate that a total of 1.4 million protein molecules make up a single Arabidopsis mitochondrion on average. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40 000 for Voltage‐Dependent Anion Channel 1 to sub‐stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat proteins that modify mitochondrial transcripts. For our analysis, we consider the physical and chemical constraints of the single organelle and discuss prominent features of mitochondrial architecture, protein biogenesis, oxidative phosphorylation, metabolism, antioxidant defence, genome maintenance, gene expression, and dynamics. While assessing the limitations of our considerations, we exemplify how our understanding of biochemical function and structural organization of plant mitochondria can be connected in order to obtain global and specific insights into how organelles work.

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Section: Resultsmentioning

confidence: 97%

Single organelle function and organization as estimated from Arabidopsis mitochondrial proteomics

et al. 2019

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“…A recent study showed that A. thaliana MIA40 activates the phosphatase activity of an IMS‐located Shewanella‐like protein phosphatase 2 (SLP2), not found in yeast and humans, by promoting the formation of an intramolecular disulfide bridge. This interaction is important for regulating some gibberellic acid‐dependent processes during seed formation (Uhrig et al ., ).…”

Section: The Disulfide Relay In the Mitochondrial Intermembrane Spacementioning

confidence: 99%

Oxidative protein folding: state‐of‐the‐art and current avenues of research in plants

2018

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Contents Summary I. Introduction II. Formation and isomerization of disulfides in the ER and the Golgi apparatus III. The disulfide relay in the mitochondrial intermembrane space: why are plants different? IV. Disulfide bond formation on luminal proteins in thylakoids V. Conclusion Acknowledgements References SUMMARY: Disulfide bonds are post-translational modifications crucial for the structure and function of thousands of proteins. Their formation and isomerization, referred to as oxidative folding, require specific protein machineries found in oxidizing subcellular compartments, namely the endoplasmic reticulum and the associated endomembrane system, the intermembrane space of mitochondria and the thylakoid lumen of chloroplasts. At least one protein component is required for transferring electrons from substrate proteins to an acceptor that is usually molecular oxygen. For oxidation reactions, incoming reduced substrates are oxidized by thiol-oxidoreductase proteins (or domains in case of chimeric proteins), which are usually themselves oxidized by a single thiol oxidase, the enzyme generating disulfide bonds de novo. By contrast, the description of the molecular actors and pathways involved in proofreading and isomerization of misfolded proteins, which require a tightly controlled redox balance, lags behind. Herein we provide a general overview of the knowledge acquired on the systems responsible for oxidative protein folding in photosynthetic organisms, highlighting their particularities compared to other eukaryotes. Current research challenges are discussed including the importance and specificity of these oxidation systems in the context of the existence of reducing systems in the same compartments.

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“…MIA40 is one of two components of the mitochondrial intermembrane space (IMS) disulfide relay system, which ensures import of Cys-containing proteins into the IMS (Herrmann and Riemer, 2012). Arabidopsis MIA40 resides in the IMS and peroxisomes and is thought to be responsible for importing and trapping the chaperone for Mn-superoxide dismutase (CCS1), Cu/ Zn superoxide dismutase 1 (CSD1), and Shewanella-like protein phosphatase 2 (SLP2) in the IMS and the Cu/Zn CSD3 in peroxisomes (Carrie et al, 2010;Uhrig et al, 2017). Peroxisome localization has only been observed using GFP-MIA40-N terminus fusion constructs that block MYR.…”

Section: Alternative Localization Of Myred Proteins In Non-pm Compartmentioning

confidence: 99%

Targeted Profiling of Arabidopsis thaliana Subproteomes Illuminates Co- and Posttranslationally N-Terminal Myristoylated Proteins

et al. 2018

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N-terminal myristoylation, a major eukaryotic protein lipid modification, is difficult to detect in vivo and challenging to predict in silico. We developed a proteomics strategy involving subfractionation of cellular membranes, combined with separation of hydrophobic peptides by mass spectrometry-coupled liquid chromatography to identify the myristoylated proteome. This approach identified a starting pool of 8837 proteins in all analyzed cellular fractions, comprising 32% of the Arabidopsis proteome. Of these, 906 proteins contain an N-terminal Gly at position 2, a prerequisite for myristoylation, and 214 belong to the predicted myristoylome (comprising 51% of the predicted myristoylome of 421 proteins). We further show direct evidence of myristoylation in 72 proteins; 18 of these myristoylated proteins were not previously predicted. We found one myristoylation site downstream of a predicted initiation codon, indicating that posttranslational myristoylation occurs in plants. Over half of the identified proteins could be quantified and assigned to a subcellular compartment. Hierarchical clustering of protein accumulation combined with myristoylation and-acylation data revealed that N-terminal double acylation influences redirection to the plasma membrane. In a few cases, MYR function extended beyond simple membrane association. This study identified hundreds of -acylated proteins for which lipid modifications could control protein localization and expand protein function.

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Activation of Mitochondrial Protein Phosphatase SLP2 by MIA40 Regulates Seed Germination

Cited by 25 publications

References 49 publications

Single organelle function and organization as estimated from Arabidopsis mitochondrial proteomics

Single organelle function and organization as estimated from Arabidopsis mitochondrial proteomics

Oxidative protein folding: state‐of‐the‐art and current avenues of research in plants

Targeted Profiling of Arabidopsis thaliana Subproteomes Illuminates Co- and Posttranslationally N-Terminal Myristoylated Proteins

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