On the occurrence of a glutaredoxin-like small protein in the anaerobic protozoan parasite Entamoeba histolytica.

Background: Entamoeba histolytica, an intestinal parasitic protozoan that usually lives and multiplies within the human gut, is the causative agent of amoebiasis. To date, de novo glutathione biosynthesis and its associated enzymes have not been identified in the parasite. Cysteine has been proposed to be the main intracellular thiol.

Transforming growth factor β1 upregulates 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase-4 expression in A549 and MCF-10A cells.

Transforming growth factor β1 (TGFβ1) induces a cellular process known as epithelial-mesenchymal transition (EMT) associated with metabolic reprogramming, including enhanced glycolysis. Given the involvement of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFKFB) enzymes in glycolysis, we aimed to investigate whether TGFβ1 regulates expressions of PFKFB genes and if PFKFBs are required for TGFβ1-driven phenotypes. A549 and MCF-10A cell lines were used as TGFβ1-driven EMT models.

Integrating multiple regulations on enzyme activity: the case of phosphopyruvate carboxykinases.

Data on protein post-translational modifications (PTMs) increased exponentially in the last years due to the refinement of mass spectrometry techniques and the development of databases to store and share datasets. Nevertheless, these data per se do not create comprehensive biochemical knowledge. Complementary studies on protein biochemistry are necessary to fully understand the function of these PTMs at the molecular level and beyond, for example, designing rational metabolic engineering strategies to improve crops.

A critical inter-subunit interaction for the transmission of the allosteric signal in the Agrobacterium tumefaciens ADP-glucose pyrophosphorylase.

ADP-glucose pyrophosphorylase is a key regulatory enzyme involved in starch and glycogen synthesis in plants and bacteria, respectively. It has been hypothesized that inter-subunit communications are important for the allosteric effect in this enzyme. However, no specific interactions have been identified as part of the regulatory signal.

Biochemical characterization of GAF domain of free-R-methionine sulfoxide reductase from Trypanosoma cruzi.

Trypanosoma cruzi is the causal agent of Chagas Disease and is a unicellular parasite that infects a wide variety of mammalian hosts. The parasite exhibits auxotrophy by L-Met; consequently, it must be acquired from the extracellular environment of the host, either mammalian or invertebrate. Methionine (Met) oxidation produces a racemic mixture (R and S forms) of methionine sulfoxide (MetSO).

The involvement of allosteric effectors and post-translational modifications in the control of plant central carbon metabolism.

Plant metabolism is finely orchestrated to allow the occurrence of complementary and sometimes opposite metabolic pathways. In part this is achieved by the allosteric regulation of enzymes, which has been a cornerstone of plant research for many decades. The completion of the Arabidopsis genome and the development of the associated toolkits for Arabidopsis research moved the focus of many researchers to other fields.

Insights to improve the activity of glycosyl phosphorylases from Ruminococcus 8 with cello-oligosaccharides.

The phosphorolysis of cello-oligosaccharides is a critical process played in the rumen by to degrade cellulose. Cellodextrins, made up of a few glucosyl units, have gained lots of interest by their potential applications. Here, we characterized a cellobiose phosphorylase (CBP) and a cellodextrin phosphorylase (CDP) from 8.

Functional and structural characterization of an endo-β-1,3-glucanase from Euglena gracilis.

Endo-β-1,3-glucanases from several organisms have attracted much attention in recent years because of their capability for in vitro degrading β-1,3-glucan as a critical step for both biofuels production and short-chain oligosaccharides synthesis. In this study, we biochemically characterized a putative endo-β-1,3-glucanase (EgrGH64) belonging to the family GH64 from the single-cell protist Euglena gracilis. The gene coding for the enzyme was heterologously expressed in a prokaryotic expression system supplemented with 3% (v/v) ethanol to optimize the recombinant protein right folding.

Phosphorylation of aldose-6-phosphate reductase from Prunus persica leaves.

Sugar-alcohols are major photosynthates in plants from the Rosaceae family. Expression of the gene encoding aldose-6-phosphate reductase (Ald6PRase), the critical enzyme for glucitol synthesis in rosaceous species, is regulated by physiological and environmental cues. Additionally, Ald6PRase is inhibited by small molecules (hexose-phosphates and inorganic orthophosphate) and oxidizing compounds.

Structural Determinants of Sugar Alcohol Biosynthesis in Plants: The Crystal Structures of Mannose-6-Phosphate and Aldose-6-Phosphate Reductases.

Sugar alcohols are major photosynthetic products in plant species from the Apiaceae and Plantaginaceae families. Mannose-6-phosphate reductase (Man6PRase) and aldose-6-phosphate reductase (Ald6PRase) are key enzymes for synthesizing mannitol and glucitol in celery (Apium graveolens) and peach (Prunus persica), respectively. In this work, we report the first crystal structures of dimeric plant aldo/keto reductases (AKRs), celery Man6PRase (solved in the presence of mannonic acid and NADP+) and peach Ald6PRase (obtained in the apo form).

Functional characterization of monothiol and dithiol glutaredoxins from Leptospira interrogans.

Thiol redox proteins and low molecular mass thiols have essential functions in maintaining cellular redox balance in almost all living organisms. In the pathogenic bacterium Leptospira interrogans, several redox components have been described, namely, typical 2-Cys peroxiredoxin, a functional thioredoxin system, glutathione synthesis pathway, and methionine sulfoxide reductases. However, until now, information about proteins linked to GSH metabolism has not been reported in this pathogen.

Structure, function, and evolution of plant ADP-glucose pyrophosphorylase.

This review outlines research performed in the last two decades on the structural, kinetic, regulatory and evolutionary aspects of ADP-glucose pyrophosphorylase, the regulatory enzyme for starch biosynthesis. ADP-glucose pyrophosphorylase (ADP-Glc PPase) catalyzes the first committed step in the pathway of glycogen and starch synthesis in bacteria and plants, respectively. Plant ADP-Glc PPase is a heterotetramer allosterically regulated by metabolites and post-translational modifications.

The ADP-glucose pyrophosphorylase from Melainabacteria: a comparative study between photosynthetic and non-photosynthetic bacterial sources.

Until recently, the cyanobacterial phylum only included oxygenic photosynthesizer members. The discovery of Melainabacteria as a group of supposed non-photosynthetic cyanobacteria asked to revisit such scenario. From metagenomic data, we were able to identify sequences encoding putative ADP-glucose pyrophosphorylases (ADP-GlcPPase) from free-living and intestinal Melainabacteria.

Simultaneous inhibition of PFKFB3 and GLS1 selectively kills KRAS-transformed pancreatic cells.

Activating mutations of the oncogenic KRAS in pancreatic ductal adenocarcinoma (PDAC) are associated with an aberrant metabolic phenotype that may be therapeutically exploited. Increased glutamine utilization via glutaminase-1 (GLS1) is one such feature of the activated KRAS signaling that is essential to cell survival and proliferation; however, metabolic plasticity of PDAC cells allow them to adapt to GLS1 inhibition via various mechanisms including activation of glycolysis, suggesting a requirement for combinatorial anti-metabolic approaches to combat PDAC. We investigated whether targeting the glycolytic regulator 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) in combination with GLS1 can selectively prevent the growth of KRAS-transformed cells.

Tyr-Asp inhibition of glyceraldehyde 3-phosphate dehydrogenase affects plant redox metabolism.

How organisms integrate metabolism with the external environment is a central question in biology. Here, we describe a novel regulatory small molecule, a proteogenic dipeptide Tyr-Asp, which improves plant tolerance to oxidative stress by directly interfering with glucose metabolism. Specifically, Tyr-Asp inhibits the activity of a key glycolytic enzyme, glyceraldehyde 3-phosphate dehydrogenase (GAPC), and redirects glucose toward pentose phosphate pathway (PPP) and NADPH production.

Nucleotide-sugar metabolism in plants: the legacy of Luis F. Leloir.

This review commemorates the 50th anniversary of the Nobel Prize in Chemistry awarded to Luis F. Leloir 'for his discovery of sugar-nucleotides and their role in the biosynthesis of carbohydrates'. He and his co-workers discovered that activated forms of simple sugars, such as UDP-glucose and UDP-galactose, are essential intermediates in the interconversion of sugars.

Elucidating carbohydrate metabolism in Euglena gracilis: Reverse genetics-based evaluation of genes coding for enzymes linked to paramylon accumulation.

Euglena gracilis is a eukaryotic single-celled and photosynthetic organism grouped under the kingdom Protista. This phytoflagellate can accumulate the carbon photoassimilate as a linear β-1,3-glucan chain called paramylon. This storage polysaccharide can undergo degradation to provide glucose units to obtain ATP and reducing power both in aerobic and anaerobic growth conditions.

Proteolytic cleavage of Arabidopsis thaliana phosphoenolpyruvate carboxykinase-1 modifies its allosteric regulation.

Phosphoenolpyruvate carboxykinase (PEPCK) plays a crucial role in gluconeogenesis. In this work, we analyze the proteolysis of Arabidopsis thaliana PEPCK1 (AthPEPCK1) in germinating seedlings. We found that the amount of AthPEPCK1 protein peaks at 24-48 h post-imbibition.

Functional characterization of methionine sulfoxide reductases from Leptospira interrogans.

Background: Methionine (Met) oxidation leads to a racemic mixture of R and S forms of methionine sulfoxide (MetSO). Methionine sulfoxide reductases (Msr) are enzymes that can reduce specifically each isomer of MetSO, both free and protein-bound. The Met oxidation could change the structure and function of many proteins, not only of those redox-related but also of others involved in different metabolic pathways.

On the functionality of the N-terminal domain in xylanase 10A from Ruminococcus albus 8.

We analyzed the structure to function relationships in Ruminococcus albus 8 xylanase 10A (RalXyn10A) finding that the N-terminus 34-amino acids sequence (N34) in the protein is particularly functional. We performed the recombinant wild type enzyme's characterization and that of the truncated mutant lacking the N34 extreme (RalΔN34Xyn10A). The truncated enzyme exhibited about half of the activity and reduced affinity for binding to insoluble saccharides.

Biochemical characterization of recombinant UDP-sugar pyrophosphorylase and galactinol synthase from Brachypodium distachyon.

Raffinose (Raf) protects plant cells during seed desiccation and under different abiotic stress conditions. The biosynthesis of Raf starts with the production of UDP-galactose by UDP-sugar pyrophosphorylase (USPPase) and continues with the synthesis of galactinol by galactinol synthase (GolSase). Galactinol is then used by Raf synthase to produce Raf.

Phosphorylation of ADP-Glucose Pyrophosphorylase During Wheat Seeds Development.

Starch is the dominant reserve polysaccharide accumulated in the seed of grasses (like wheat). It is the most common carbohydrate in the human diet and a material applied to the bioplastics and biofuels industry. Hence, the complete understanding of starch metabolism is critical to design rational strategies to improve its allocation in plant reserve tissues.