Michael Hodges

Michael Hodges
Université Paris-Sud 11 | Paris 11 · Institute of Plant Sciences Paris-Saclay

BSc PhD

About

135
Publications
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Publications

Publications (135)
Article
Full-text available
DspA/E is a type three effector injected by the pathogenic bacterium Erwinia amylovora inside plant cells. In non-host Arabidopsis thaliana, DspA/E inhibits seed germination, root growth, de novo protein synthesis and triggers localized cell death. To better understand the mechanisms involved, we performed EMS mutagenesis on a transgenic line, 13-1...
Article
Full-text available
Photorespiration is a metabolic process that removes toxic 2-phosphoglycolate produced by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase. It is essential for plant growth under ambient air, and it can play an important role under stress conditions that reduce CO2 entry into the leaf thus enhancing photorespiration. The ai...
Article
Phosphoglycerate mutases (PGAMs) catalyse the reversible isomerisation of 3‐phosphoglycerate and 2‐phosphoglycerate, a step of glycolysis. PGAMs can be sub‐divided into 2,3‐biphosphoglycerate dependent (dPGAM) and independent (iPGAM) enzymes. In plants, phosphoglycerate isomerisation is carried out by cytosolic iPGAM. Despite its crucial role in ca...
Article
Full-text available
Leaf senescence in source leaves leads to the active degradation of chloroplast components [photosystems, chlorophylls, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)] and plays a key role in the efficient remobilization of nutrients toward sink tissues. However, the progression of leaf senescence can differentially modify the photosynth...
Chapter
This chapter is dedicated to the memory of Pierre Gadal a former Series Editor for Advances in Botanical Research. Its aim is to describe the research that has been done in his laboratory covering essentially the period 1970–2000 and provides first-hand testimony about how it has been done. Besides the scientific output concerning CO2 and nitrogen...
Article
Photorespiration is an essential process in oxygenic photosynthetic organisms triggered by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase. In peroxisomes, photorespiratory HYDROXYPYRUVATE REDUCTASE 1 (HPR1) catalyzes the conversion of hydroxypyruvate to glycerate together with the oxidation of a pyridine nucleotide cofact...
Article
Full-text available
In photosynthetic organisms, the photorespiratory cycle is an essential pathway leading to the recycling of 2-phosphoglycolate, produced by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, to 3-phosphoglycerate. Although photorespiration is a widely studied process, its regulation remains poorly understood. In this context...
Article
The photorespiratory cycle is a crucial pathway in photosynthetic organisms since it removes toxic 2‐phosphoglycolate made by the oxygenase activity of ribulose‐1,5‐bisphosphate carboxylase/oxygenase and retrieves its carbon as 3‐phosphoglycerate. Mitochondrial serine hydroxymethyltransferase 1 (SHMT1) is an essential photorespiratory enzyme conver...
Article
The analysis of complex mixtures by NMR is a challenge in (bio)chemistry due to signal overcrowding making the analysis difficult. Thus, new advanced quantitative 2D NMR techniques that lead to better resolved and more intense signals have been applied to extracts of plants for tracking biomarkers of the photosynthesis and photorespiration cycles.
Article
Arabidopsis thaliana SNF1-Related-Kinase1 (SnRK1)-Activating Kinase 1 and 2 (AtSnAK1 and 2) have been shown to phosphorylate in vitro and activate the energy signalling integrator, SnRK1. To clarify this signalling cascade in planta, a genetic- and molecular-based approach was developed. Homozygous single AtSnAK1 and AtSnAK2 T-DNA insertional mutan...
Article
Considerable efforts are currently devoted to understand the regulation of primary carbon metabolism in plant leaves, which is known to change dramatically with environmental conditions, e.g., along light/dark transitions. Protein phosphorylation is believed to be a key factor in such a metabolic control. In fact, some studies have suggested modifi...
Article
Photorespiration is an essential high flux metabolic pathway that is found in all oxygen-producing photosynthetic organisms. It is often viewed as a closed metabolic repair pathway that serves to detoxify 2-phosphoglycolic acid and to recycle carbon to fuel the Calvin-Benson cycle. However, this view is too simplistic since the photorespiratory cyc...
Article
Photorespiration is one of the major carbon metabolism pathways in oxygen-producing photosynthetic organisms. This pathway recycles 2-phosphoglycolate (2-PG), a toxic metabolite, to 3-phosphoglycerate when ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) uses oxygen instead of carbon dioxide. The photorespiratory cycle is in competition wi...
Article
Metabolic and physiological analyses of Arabidopsis thaliana glycolate oxidase (GOX) mutant leaves were performed to understand the development of the photorespiratory phenotype after transfer from high CO2 to air. We show that two Arabidopsis genes, GOX1 and GOX2, share a redundant photorespiratory role. Air-grown single gox1 and gox2 mutants grew...
Article
Full-text available
Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL.L(-1) ). When compared to wi...
Article
Full-text available
In plants, glycolate oxidase is involved in the photorespiratory cycle, one of the major fluxes at the global scale. To clarify both the nature of the mechanism and possible differences in glycolate oxidase enzyme chemistry from C3 and C4 plant species, we analyzed kinetic parameters of purified recombinant C3 (Arabidopsis thaliana) and C4 (Zea may...
Article
Phototropin-dependent chloroplast movement is essential to the photosynthetic acclimation of mesophyll cells to incident light. Chloroplast movement involves many cellular actors, such as chloroplast-associated actin filaments and proteins that mediate signalling between phototropins and chloroplast motion. In the past few years, genetic approaches...
Article
Full-text available
Cellulose is one of the most important organic compounds in terrestrial ecosystems and represents a major plant structural polymer. However, knowledge of the regulation of cellulose biosynthesis is still rather limited. Recent studies have shown that the phosphorylation of cellulose synthases (CESAs) may represent a key regulatory event in cellulos...
Poster
Full-text available
As sessile organisms, plants must adapt to changing environmental conditions that affect their optimal growth and development. Recent studies have highlig hted the importance of a central molecule in redox and respiratory metabolism, nicotinamide aden ine dinucleotide (NAD), in the metabolic signaling in plants and animals. They suggest that NAD pl...
Article
Rubisco activase (RCA) is an ancillary photosynthetic protein essential for Rubisco activity. Some data suggest that post-translational modifications (such as reduction of disulphide bridges) are involved in the regulation of RCA activity. However, despite the key role of protein phosphorylation in general metabolic regulation, RCA phosphorylation...
Article
Full-text available
Photosynthetic CO2 assimilation is the carbon source for plant anabolism, including amino acid production and protein synthesis. The biosynthesis of leaf proteins is known for decades to correlate with photosynthetic activity but the mechanisms controlling this effect are not documented. The cornerstone of the regulation of protein synthesis is bel...
Data
Phosphopeptides identified using nanoLC-MS/MS. (DOCX)
Data
Eukaryotic initiation factors and ribosomal proteins indentified by nanoLC-MS/MS. (DOCX)
Article
The cornerstone of carbon (C) and nitrogen (N) metabolic interactions - respiration - is presently not well understood in plant cells: the source of the key intermediate 2-oxoglutarate (2OG), to which reduced N is combined to yield glutamate and glutamine, remains somewhat unclear. We took advantage of combined mutations of NAD- and NADP-dependent...
Article
SNF1-Related protein Kinase-1 (SnRK1), the plant kinase homolog of mammalian AMP-activated protein Kinase (AMPK), is a sensor maintaining cellular energy homeostasis via the control of anabolism/catabolism balance. It was previously described that AMPK-dependent phosphorylation of p27(KIP) (1) impacts on cell cycle progression, autophagy and apopto...
Article
Photorespiration allows the recycling of carbon atoms of 2-phosphoglycolate produced by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) oxygenase activity, as well as the removal of potentially toxic metabolites. The photorespiratory pathway takes place in the light, encompasses four cellular compartments and interacts with several other...
Article
Full-text available
Nitrogen isotope composition (δ(15) N) in plant organic matter is currently used as a natural tracer of nitrogen acquisition efficiency. However, the δ(15) N value of whole leaf material does not properly reflect the way in which N is assimilated because isotope fractionations along metabolic reactions may cause substantial differences among leaf c...
Article
Leaf respiration is a major metabolic process that drives energy production and growth. Earlier works in this field were focused on the measurement of respiration rates in relation to carbohydrate content, photosynthesis, enzymatic activities or nitrogen content. Recently, several studies have shed light on the mechanisms describing the regulation...
Article
Natural (13)C abundance is now an unavoidable tool to study ecosystem and plant carbon economies. A growing number of studies take advantage of isotopic fractionation between carbon pools or (13)C abundance in respiratory CO(2) to examine the carbon source of respiration, plant biomass production or organic matter sequestration in soils. (12)C/(13)...
Article
Full-text available
Considerable advances in our understanding of the control of mitochondrial metabolism and its interactions with nitrogen metabolism and associated carbon/nitrogen interactions have occurred in recent years, particularly highlighting important roles in cellular redox homeostasis. The tricarboxylic acid (TCA) cycle is a central metabolic hub for the...
Article
The PII protein is an integrator of central metabolism and energy levels. In Arabidopsis, allosteric sensing of cellular energy and carbon levels alters the ability of PII to interact with target enzymes such as N-acetyl-l-glutamate kinase and heteromeric acetyl-coenzyme A carboxylase, thereby modulating the biological activity of these plastidial...
Article
Full-text available
*Nitrogen assimilation in leaves requires primary NH(2) acceptors that, in turn, originate from primary carbon metabolism. Respiratory metabolism is believed to provide such acceptors (such as 2-oxoglutarate), so that day respiration is commonly seen as a cornerstone for nitrogen assimilation into glutamate in illuminated leaves. However, both glyc...
Article
Cytosolic NADP-dependent isocitrate dehydrogenase (cICDH) produces 2-oxoglutarate (2-OG) and NADPH, and is encoded by a single gene in Arabidopsis thaliana. Three allelic lines carrying T-DNA insertions in this gene showed less than 10% extractable leaf ICDH activity, but only relatively small decreases in growth compared to wild-type Col0. Metabol...
Article
Full-text available
Arabidopsis thaliana sucrose nonfermenting 1-related protein kinase 1 complexes belong to the SNF1/AMPK/SnRK1 protein kinase family that shares an ancestral function as central regulators of metabolism. In A. thaliana, the products of AtSnAK1 and AtSnAK2, orthologous to yeast genes, have been shown to autophosphorylate and to phosphorylate/activate...
Article
Full-text available
Transgenic tomato (Solanum lycopersicum) plants were generated expressing a fragment of the mitochondrial NAD-dependent isocitrate dehydrogenase gene (SlIDH1) in the antisense orientation. The transgenic plants displayed a mild reduction in the activity of the target enzyme in the leaves but essentially no visible alteration in growth from the wild...
Article
Full-text available
The PII protein is a signal integrator involved in the regulation of nitrogen metabolism in bacteria and plants. Upon sensing of cellular carbon and energy availability, PII conveys the signal by interacting with target proteins, thereby modulating their biological activity. Plant PII is located to plastids; therefore, to identify new PII target pr...
Article
Full-text available
While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-...
Article
The metabolic control of the interaction between ArabidopsisN-acetyl-l-glutamate kinase (NAGK) and the PII protein has been studied. Both gel exclusion and affinity chromatography analyses of recombinant, affinity-purified PII (trimeric complex) and NAGK (hexameric complex) showed that NAGK strongly interacted with PII only in the presence of Mg-AT...
Article
Two phosphoenolpyruvate carboxylase (PEPC) kinase genes (PPCk1 and PPCk2) are present in the Arabidopsis genome; only PPCk1 is expressed in rosette leaves. Homozygous lines of two independent PPCk1 T-DNA-insertional mutants showed very little (dln1), or no (csi8) light-induced PEPC phosphorylation and a clear retard in growth under our greenhouse c...
Article
In higher plants, the PII protein is a nuclear-encoded plastid protein that regulates the activity of a key enzyme of arginine biosynthesis. We have previously observed that Arabidopsis PII mutants are more sensitive to nitrite toxicity. Using intact chloroplasts isolated from Arabidopsis leaves and (15)N-labelled nitrite we show that a light-depen...
Article
Screening of the Arabidopsis thaliana genome revealed three potential homologues of mammalian and yeast mitochondrial DICs (dicarboxylate carriers) designated as DIC1, DIC2 and DIC3, each belonging to the mitochondrial carrier protein family. DIC1 and DIC2 are broadly expressed at comparable levels in all the tissues investigated. DIC1-DIC3 have be...
Article
Full-text available
Day respiration is the process by which nonphotorespiratory CO2 is produced by illuminated leaves. The biological function of day respiratory metabolism is a major conundrum of plant photosynthesis research: because the rate of CO2 evolution is partly inhibited in the light, it is viewed as either detrimental to plant carbon balance or necessary fo...
Article
Full-text available
Intense efforts are currently devoted to elucidate the metabolic networks of plants, in which nitrogen assimilation is of particular importance because it is strongly related to plant growth. In addition, at the leaf level, primary nitrogen metabolism interacts with photosynthesis, day respiration, and photorespiration, simply because nitrogen assi...
Article
Full-text available
NAD-dependent isocitrate dehydrogenase (IDH) is a tricarboxylic acid cycle enzyme that produces 2-oxoglutarate, an organic acid required by the glutamine synthetase/glutamate synthase cycle to assimilate ammonium. Three Arabidopsis (Arabidopsis thaliana) IDH mutants have been characterized, corresponding to an insertion into a different IDH gene (A...
Article
Full-text available
NAD-dependent isocitrate dehydrogenase (IDH) is a Krebs cycle enzyme situated in mitochondria. In Arabidopsis thaliana, five genes encode functional IDH subunits that can be classed into two groups based on gene structure and subunit amino acid sequence. Arabidopsis contains two 'catalytic' and three 'regulatory' subunits according to their homolog...
Article
In higher plants, PII is a nuclear-encoded plastid protein which is homologous to bacterial PII signalling proteins known to be involved in the regulation of nitrogen metabolism. A reduced ornithine, citrulline and arginine accumulation was observed in two Arabidopsis PII knock-out mutants in response to NH4+ resupply after N starvation. This diffe...
Chapter
Phosphoenolpyruvate carboxylase (PEPc) is a multifaceted enzyme that serves different physiological functions in plants. In C3 plants, an important role is in the anaplerotic supply of carbon skeletons for biosynthetic functions such as amino acid synthesis, whereas C4 and crassulacean acid metabolism (CAM) species also have a specific, highly acti...
Article
The PII signal transducing protein is involved in carbon/nitrogen (C/N) sensing in bacteria and cyanobacteria. In higher plants the function of the PII homolog GLB1 is not known. GLB1 transcripts were found in all plant organs tested, while in Arabidopsis leaves GLB1 expression and PII protein levels were not significantly affected by either the da...
Article
Full-text available
The four phosphoenolpyruvate carboxylase encoding genes (1–4) of Arabidopsis thaliana were found to be expressed in rosette leaves, with PEPC2 mRNA being the major species. The enzyme activity was sensitive to feedback inhibition by malate, aspartate and glutamate and this effect was antagonized by glucose-6-phosphate and modulated after a dark–lig...
Article
In rice roots, transient and cell-type-specific accumulation of both mRNA and protein for NADH-dependent glutamate synthase (NADH-GOGAT) occurs after the supply of NH4 + ions. In order to better understand the origin of 2-oxoglutarate for this reaction, we focused on mitochondrial NAD-dependent isocitrate dehydrogenase (IDH) and glutamate dehydrog...
Article
Plant mitochondria maintain metabolic communication with the cytosol through a family of carrier proteins that share several structural features. Early studies led to the recognition of several mitochondrial transport activities but the proteins responsible for these activities had not been identified. The in silico analysis of the complete Arabido...
Article
Full-text available
Like many other soluble chloroplastic enzymes, thioredoxin f is nuclear-encoded and expressed as a precursor protein. After synthesis in the cytosol, it is imported into the chloroplast with subsequent cleavage of the transit sequence in the stroma. We report the expression and the partial purification of the recombinant precursor thioredoxin f pro...
Chapter
The metabolic communication between plant mitochondria and the cytosol requires the flux of metabolites, nucleotides and cofactors across the inner mitochondrial membrane. This is accomplished by a family of mitochondrial carrier pro-teins (better characterized in animal and yeast) that span the inner membrane lipid bilayer and share distinct commo...
Article
The assimilation of ammonium into glutamate is mainly achieved by the GS/GOGAT pathway and requires carbon skeletons in the form of 2-oxoglutarate. To date, the exact enzymatic origin of this organic acid for plant ammonium assimilation is unknown. NADP+-dependent isocitrate dehydrogenases can carry out this function and the recent efforts concentr...
Article
Full-text available
This review examines the current understanding of the structural, functional and regulatory properties of C4 and C3 forms of higher plant phosphoenolpyruvate carboxylase. The emphasis is on the interactive metabolic and post‐translational controls acting on the enzyme in the physiological context of C4 photosynthesis and the anaplerotic pathway. A...
Article
Full-text available
A cDNA from Arabidopsis thalianaand four related cDNAs from Nicotiana tabacum that we have isolated encode hitherto unidentified members of the mitochondrial carrier family. These proteins have been overexpressed in bacteria and reconstituted into phospholipid vesicles. Their transport properties demonstrate that they are orthologs/isoforms of a no...
Article
The metabolic cross-talk associated with re-assimilation of photorespiratory NH4+ was analysed in transformed tobacco (Nicotiana tabacum L.) plants with low activities of ferredoxin-dependent glutamine-alpha-ketoglutarate aminotransferase (Fd-GOGAT; EC 1.4.7.1). Amounts of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco; EC 4.1.1.39) prote...