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Iddar, Abdelghani; Valverde, Federico; Serrano, Aurelio; Soukri, Abdelaziz

doi:10.1023/a:1024112027440

Cited by 28 publications

(11 citation statements)

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“…The oxidative branch of the pentose pathway, with G6PDH as a key enzyme, generates NADPH in all organisms, in human and in yeast cells represented by single isoforms and in plants by six isoforms [ 55 ]. In addition, plants and bacteria possess a highly stable GapN [ 54 , 56 ], which is a prime candidate for additional NADPH production in stressful conditions.…”

Section: Resultsmentioning

confidence: 99%

Cytosolic GAPDH as a redox-dependent regulator of energy metabolism

et al. 2018

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BackgroundPlant cytosolic NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GapC) displays redox-dependent changes in its subcellular localizations and activity. Apart from its fundamental role in glycolysis, it also exhibits moonlighting properties. Since the exceptional redox-sensitivity of GapC has been suggested to play a crucial role in its various functions, we here studied its redox-dependent subcellular localization and the influence of the redox-state on GapC protein interactions.ResultsIn mesophyll protoplasts from Arabidopsis thaliana, colocalization of GapC with mitochondria was more pronounced under reducing conditions than upon oxidative stress. In accordance, reduced GapC showed an increased affinity to the mitochondrial voltage-dependent anion-selective channel (VDAC) compared to the oxidized one. On the other hand, nuclear localization of GapC was increased under oxidizing conditions. The essential role of the catalytic cysteine for nuclear translocation was shown by using the corresponding cysteine mutants. Furthermore, interaction of GapC with the thioredoxin Trx-h3 as a candidate to revert the redox-modifications, occurred in the nucleus of oxidized protoplasts. In a yeast complementation assay, we could demonstrate that the plant-specific non-phosphorylating glyceraldehyde 3-P dehydrogenase (GapN) can substitute for glucose 6-P dehydrogenase to generate NADPH for re-reduction of the Trx system and ROS defense.ConclusionsThe preferred association of reduced, glycolytically active GapC with VDAC suggests a substrate-channeling metabolon at the mitochondrial surface for efficient energy generation. Increased occurrence of oxidized GapC in the nucleus points to a function in signal transduction and gene expression. Furthermore, the interaction of GapC with Trx-h3 in the nucleus indicates reversal of the oxidative cysteine modification after re-establishment of cellular homeostasis. Both, energy metabolism and signal transfer for long-term adjustment and protection from redox-imbalances are mediated by the various functions of GapC. The molecular properties of GapC as a redox-switch are key to its multiple roles in orchestrating energy metabolism.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1390-6) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Cytosolic GAPDH as a redox-dependent regulator of energy metabolism

et al. 2018

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“…However, early reports of GAPN activity in Streptococcus mutans were later confirmed by the characterization of the first prokaryotic GAPN (Crow and Wittenberger, 1979 ; Boyd et al, 1995 ). Since then, GAPN has also been found in various (hyper)thermophilic archaea, such as Thermococcus kodakarensis, Thermoproteus tenax , and Sulfolobus solfataricus (Brunner et al, 1998 ; Ettema et al, 2008 ; Matsubara et al, 2011 ), and several gram-positive bacteria, such as Clostridium acetobutylicum, Streptococcus pyogenes , and Bacillus halodurans (Table 1 ) (Iddar et al, 2002 , 2003 , 2005 ; Sophos and Vasiliou, 2003 ; Agledal et al, 2010 ). GAPN catalyzes the irreversible, non-phosphorylating oxidation of GAP to 3-PG with the concurrent reduction of NADP + to NADPH:

In this reaction, 1,3-BPG is not formed, and the oxidation of GAP is not coupled to the generation of ATP (Figure 4 ).…”

Section: Nadph-generating Reactions Coupled To Central Carbon Metabolmentioning

confidence: 99%

NADPH-generating systems in bacteria and archaea

et al. 2015

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Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms. It provides the reducing power that drives numerous anabolic reactions, including those responsible for the biosynthesis of all major cell components and many products in biotechnology. The efficient synthesis of many of these products, however, is limited by the rate of NADPH regeneration. Hence, a thorough understanding of the reactions involved in the generation of NADPH is required to increase its turnover through rational strain improvement. Traditionally, the main engineering targets for increasing NADPH availability have included the dehydrogenase reactions of the oxidative pentose phosphate pathway and the isocitrate dehydrogenase step of the tricarboxylic acid (TCA) cycle. However, the importance of alternative NADPH-generating reactions has recently become evident. In the current review, the major canonical and non-canonical reactions involved in the production and regeneration of NADPH in prokaryotes are described, and their key enzymes are discussed. In addition, an overview of how different enzymes have been applied to increase NADPH availability and thereby enhance productivity is provided.

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“…This family of proteins were initially identified in and thought to occur exclusively in the so-called green eukaryotes. More recently, ND-G3PDH homologs have been identified in several Gram-positive organisms [ 21 , 24 , 25 ].…”

Section: Resultsmentioning

confidence: 99%

The Rhodococcus opacus TadD protein mediates triacylglycerol metabolism by regulating intracellular NAD(P)H pools

MacEachran

Sinskey

2013

Microb Cell Fact

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BackgroundThe Gram-positive actinomycete Rhodococcus opacus is widely studied for its innate ability to store large amounts of carbon in the form of triacylglycerol (TAG). Several groups have demonstrated that R. opacus PD630 is capable of storing anywhere from 50 to 76% of its cell dry weight as TAG. While numerous studies have focused on phenomenological aspects of this process, few have sought to identify the underlying molecular and biochemical mechanisms responsible for the biosynthesis and storage of this molecule.ResultsHerein we further our previous efforts to illuminate the black box that is lipid metabolism in actinomycetes using a genetic approach. Utilizing a simple, colorimetric genetic screen, we have identified a gene, referred to herein as tadD (triacylglycerol accumulation deficient), which is critical for TAG biosynthesis in R. opacus PD630. Furthermore, we demonstrate that the purified protein product of this gene is capable of oxidizing glyceraldehyde-3-phosphate, while simultaneously reducing NAD(P)+ to NAD(P)H. Supporting this biochemical data, we observed that the ratio of NAD(P)H to NAD(P)+ is elevated in wildtype cultures grown under lipid production conditions as compared to cultures grown under vegetative growth conditions, while the mutant strain demonstrated no change irrespective of growth conditions. Finally, we demonstrate that over-expressing a putative phosphorylative glyceraldehyde-3-phosphate dehydrogenase leads to decreased TAG production during growth on TAG accumulation conditions.ConclusionTaken together, the data support the identification of a key metabolic branch point separating vegetative growth and lipid accumulation lifestyles in Rhodococcus.

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Untitled

Cited by 28 publications

References 30 publications

Cytosolic GAPDH as a redox-dependent regulator of energy metabolism

Cytosolic GAPDH as a redox-dependent regulator of energy metabolism

NADPH-generating systems in bacteria and archaea

The Rhodococcus opacus TadD protein mediates triacylglycerol metabolism by regulating intracellular NAD(P)H pools

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