Structural Analysis of Hexokinase Provides Novel Information about Catalysis Due to a -Specific Insertion.

The protozoan parasite is the causative pathogen of the most severe form of malaria, for which novel strategies for treatment are urgently required. The primary energy supply for intraerythrocytic stages of is the production of ATP via glycolysis. Due to the parasite's strong dependence on this pathway and the significant structural differences of its glycolytic enzymes compared to its human counterpart, glycolysis is considered a potential drug target.

Structure of 6-Phosphogluconate Dehydrogenase and Inhibition by Phosphine Gold(I) Complexes: A Potential Approach to Leishmaniasis Treatment.

As unicellular parasites are highly dependent on NADPH as a source for reducing equivalents, the main NADPH-producing enzymes glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) of the pentose phosphate pathway are considered promising antitrypanosomatid drug targets. Here we present the biochemical characterization and crystal structure of 6PGD (6PGD) in complex with NADP(H). Most interestingly, a previously unknown conformation of NADPH is visible in this structure.

Crystal structure of plasmoredoxin, a redox-active protein unique for malaria parasites.

Plasmoredoxin is a 22 ​kDa thiol-disulfide oxidoreductase involved in cellular redox regulatory processes and antioxidant defense. The 1.6 ​Å structure of the protein, solved via X-ray crystallography, adopts a modified thioredoxin fold.

Structure and Function of Redox-Sensitive Superfolder Green Fluorescent Protein Variant.

Genetically encoded green fluorescent protein (GFP)-based redox biosensors are widely used to monitor specific and dynamic redox processes in living cells. Over the last few years, various biosensors for a variety of applications were engineered and enhanced to match the organism and cellular environments, which should be investigated. In this context, the unicellular intraerythrocytic parasite , the causative agent of malaria, represents a challenge, as the small size of the organism results in weak fluorescence signals that complicate precise measurements, especially for cell compartment-specific observations.

Galectin-8 binds to the Farnesylated C-terminus of K-Ras4B and Modifies Ras/ERK Signaling and Migration in Pancreatic and Lung Carcinoma Cells.

K-Ras is the most prominent driver of oncogenesis and no effective K-Ras inhibitors have been established despite decades of intensive research. Identifying new K-Ras-binding proteins and their interaction domains offers the opportunity for defining new approaches in tackling oncogenic K-Ras. We have identified Galectin-8 as a novel, direct binding protein for K-Ras4B by mass spectrometry analyses and protein interaction studies.

Elucidating the Immune Evasion Mechanisms of , the Causative Agent of Lyme Disease.

sp. nov. has recently been reported as a novel human pathogenic spirochete causing Lyme disease (LD) in North America.

Phosphoproteome Analysis of Cells Infected with Adapted and Nonadapted Influenza A Virus Reveals Novel Pro- and Antiviral Signaling Networks.

Influenza A viruses (IAVs) quickly adapt to new environments and are well known to cross species barriers. To reveal a molecular basis for these phenomena, we compared the Ser/Thr and Tyr phosphoproteomes of murine lung epithelial cells early and late after infection with mouse-adapted SC35M virus or its nonadapted SC35 counterpart. With this analysis we identified a large set of upregulated Ser/Thr phosphorylations common to both viral genotypes, while Tyr phosphorylations showed little overlap.

Characterization of Plasmodium falciparum 6-Phosphogluconate Dehydrogenase as an Antimalarial Drug Target.

The enzyme 6-phosphogluconate dehydrogenase (6PGD) of the malaria parasite Plasmodium falciparum catalyzes the third step of the pentose phosphate pathway converting 6-phosphogluconate (6PG) to ribulose 5-phosphate. The NADPH produced by 6PGD is crucial for antioxidant defense and redox regulation, and ribose 5-phosphate is essential for DNA and RNA synthesis in the rapidly growing parasite. Thus, 6PGD represents an attractive antimalarial drug target.

Kinetic characterization of wild-type and mutant human thioredoxin glutathione reductase defines its reaction and regulatory mechanisms.

Unlabelled: In most cells, the thioredoxin (Trx) and glutathione systems are essential in maintaining redox homeostasis. The selenoprotein thioredoxin glutathione reductase (TGR) is a hybrid enzyme in which a glutaredoxin (Grx) domain is linked to a thioredoxin reductase (TrxR). Notably, the protein is also capable of reducing glutathione disulfide (GSSG), thus representing an important link between the two redox systems.

Structural and Functional Characterization of Plasmodium falciparum Nicotinic Acid Mononucleotide Adenylyltransferase.

Nicotinic acid mononucleotide adenylyltransferase (NaMNAT) is an indispensable enzyme for the synthesis of NAD and NAD phosphate. It catalyzes the adenylylation of nicotinic acid mononucleotide (NaMN) to yield nicotinic acid adenine dinucleotide (NaAD). Since NAD(H) and NAD phosphate(H) are essentially involved in metabolic and redox regulatory reactions, NaMNAT is an attractive drug target in the fight against bacterial and parasitic infections.

Characterization and redox regulation of Plasmodium falciparum methionine adenosyltransferase.

As a methyl group donor for biochemical reactions, S-adenosylmethionine plays a central metabolic role in most organisms. Depletion of S-adenosylmethionine has downstream effects on polyamine metabolism and methylation reactions, and is an effective way to combat pathogenic microorganisms such as malaria parasites. Inhibition of both the methylation cycle and polyamine synthesis strongly affects Plasmodium falciparum growth.

Characterization of the 26S proteasome network in Plasmodium falciparum.

In eukaryotic cells, the ubiquitin-proteasome system as a key regulator of protein quality control is an excellent drug target. We therefore aimed to analyze the 26S proteasome complex in the malaria parasite Plasmodium falciparum, which still threatens almost half of the world's population. First, we established an affinity purification protocol allowing for the isolation of functional 26S proteasome complexes from the parasite.

Plasmodium Apicoplast Gln-tRNAGln Biosynthesis Utilizes a Unique GatAB Amidotransferase Essential for Erythrocytic Stage Parasites.

The malaria parasite Plasmodium falciparum apicoplast indirect aminoacylation pathway utilizes a non-discriminating glutamyl-tRNA synthetase to synthesize Glu-tRNA(Gln) and a glutaminyl-tRNA amidotransferase to convert Glu-tRNA(Gln) to Gln-tRNA(Gln). Here, we show that Plasmodium falciparum and other apicomplexans possess a unique heterodimeric glutamyl-tRNA amidotransferase consisting of GatA and GatB subunits (GatAB). We localized the P.

Crystal structure of the Plasmodium falciparum thioredoxin reductase-thioredoxin complex.

Over the last decades, malaria parasites have been rapidly developing resistance against antimalarial drugs, which underlines the need for novel drug targets. Thioredoxin reductase (TrxR) is crucially involved in redox homeostasis and essential for Plasmodium falciparum. Here, we report the first crystal structure of P.

HIPK2 kinase activity depends on cis-autophosphorylation of its activation loop.

The multitude of mechanisms regulating the activity of protein kinases includes phosphorylation of amino acids contained in the activation loop. Here we show that the serine/threonine kinase HIPK2 (homeodomain-interacting protein kinase 2) is heavily modified by autophosphorylation, which occurs by cis-autophosphorylation at the activation loop and by trans-autophosphorylation at other phosphorylation sites. Cis-autophosphorylation of HIPK2 at Y354 and S357 in the activation loop is essential for its kinase function and the binding to substrates and the interaction partner Pin1.

Biochemical and structural characterization of Plasmodium falciparum glutamate dehydrogenase 2.

Glutamate dehydrogenases (GDHs) play key roles in cellular redox, amino acid, and energy metabolism, thus representing potential targets for pharmacological interventions. Here we studied the functional network provided by the three known glutamate dehydrogenases of the malaria parasite Plasmodium falciparum. The recombinant production of the previously described PfGDH1 as hexahistidyl-tagged proteins was optimized.

The bacterial redox signaller pyocyanin as an antiplasmodial agent: comparisons with its thioanalog methylene blue.

The quorum sensor and signalling molecule pyocyanin (PYO) contributes significantly to the pathophysiology of Pseudomonas aeruginosa infections. Comparison to phenothiazine drugs suggests that the antimalarial compound methylene blue (MB) can be regarded as a sulfur analog of PYO. This working hypothesis would explain why the synthetic drug MB behaves as a compound shaped in biological evolution.

Crystal structure of the human thioredoxin reductase-thioredoxin complex.

Thioredoxin reductase 1 (TrxR1) is a homodimeric flavoprotein crucially involved in the regulation of cellular redox homeostasis, growth, and differentiation. Its importance in various diseases makes TrxR1 a highly interesting drug target. Here we present the first crystal structures of human TrxR1 in complex with its substrate thioredoxin (Trx).

Mutations in the mitochondrial thioredoxin reductase gene TXNRD2 cause dilated cardiomyopathy.

Aims: Cardiac energy requirement is met to a large extent by oxidative phosphorylation in mitochondria that are highly abundant in cardiac myocytes. Human mitochondrial thioredoxin reductase (TXNRD2) is a selenocysteine-containing enzyme essential for mitochondrial oxygen radical scavenging. Cardiac-specific deletion of Txnrd2 in mice results in dilated cardiomyopathy (DCM).

Redox regulation of Plasmodium falciparum ornithine δ-aminotransferase.

Ornithine δ-aminotransferase (OAT) of the malaria parasite Plasmodium falciparum catalyzes the reversible conversion of ornithine into glutamate-5-semialdehyde and glutamate and is-in contrast to its human counterpart-activated by thioredoxin (Trx) by a factor of 10. Trx, glutaredoxin, and plasmoredoxin are redox-active proteins that play a crucial role in the maintenance and control of redox reactions, and were shown to interact with P. falciparum OAT.

Compounds structurally related to ellagic acid show improved antiplasmodial activity.

The cancer chemopreventive agent ellagic acid (EA) is a known inhibitor of glutathione S-transferases (GSTs) and possesses antiplasmodial activities in the upper-nanomolar range. In the recent drug development approach, the properties of the active site of Plasmodium falciparum GST were exploited for inhibitor design by introducing one or two additional hydroxyl groups into EA, yielding flavellagic acid (FEA) and coruleoellagic acid (CEA), respectively. Indeed, the inhibition of P.

The structure of human thioredoxin reductase 1 provides insights into C-terminal rearrangements during catalysis.

Human thioredoxin reductase (hTrxR) is a homodimeric flavoprotein crucially involved in the regulation of cellular redox reactions, growth and differentiation. The enzyme contains a selenocysteine residue at its C-terminal active site that is essential for catalysis. This redox center is located on a flexible arm, solvent-exposed and reactive towards electrophilic inhibitors, thus representing a target for antitumor drug development.