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Trends in Biochemical Sciences Nov 2022Triterpenes are C30 organic compounds abundantly found in all living organisms. Although previously believed to be exclusively produced from squalene or oxidosqualene, a...
Triterpenes are C30 organic compounds abundantly found in all living organisms. Although previously believed to be exclusively produced from squalene or oxidosqualene, a recent report by Tao and colleagues describes a new triterpene biosynthetic route involving the cyclization of the precursor hexaprenyl diphosphate (HexPP) by unprecedented bifunctional terpene synthase (TS) enzymes.
Topics: Cyclization; Diphosphates; Squalene; Triterpenes
PubMed: 35914998
DOI: 10.1016/j.tibs.2022.07.004 -
Muscle & Nerve Feb 2023
Topics: Diphosphates; Muscle, Skeletal; Radionuclide Imaging
PubMed: 36382940
DOI: 10.1002/mus.27754 -
Methods in Molecular Biology (Clifton,... 2020Acidocalcisomes are membrane-bounded, electron-dense, acidic organelles, rich in calcium and polyphosphate. These organelles were first described in trypanosomatids and...
Acidocalcisomes are membrane-bounded, electron-dense, acidic organelles, rich in calcium and polyphosphate. These organelles were first described in trypanosomatids and later found from bacteria to human cells. Some of the functions of the acidocalcisome are the storage of cations and phosphorus, participation in pyrophosphate (PP) and polyphosphate (polyP) metabolism, calcium signaling, maintenance of intracellular pH homeostasis, autophagy, and osmoregulation. Isolation of acidocalcisomes is an important technique for understanding their composition and function. Here, we provide detailed subcellular fractionation protocols using iodixanol gradient centrifugations to isolate high-quality acidocalcisomes from Trypanosoma brucei, which are subsequently validated by electron microscopy, and enzymatic and immunoblot assays with organellar markers.
Topics: Calcium Signaling; Cell Fractionation; Centrifugation, Density Gradient; Diphosphates; Enzyme Assays; Hydrogen-Ion Concentration; Microscopy, Electron; Organelles; Polyphosphates; Protozoan Proteins; Triiodobenzoic Acids; Trypanosoma brucei brucei
PubMed: 32221949
DOI: 10.1007/978-1-0716-0294-2_40 -
Cells Jan 2022Diacylglycerol pyrophosphate (DGPP) is an anionic phospholipid formed in plants, yeast, and parasites under multiple stress stimuli. It is synthesized by the...
Diacylglycerol pyrophosphate (DGPP) is an anionic phospholipid formed in plants, yeast, and parasites under multiple stress stimuli. It is synthesized by the phosphorylation action of phosphatidic acid (PA) kinase on phosphatidic acid, a signaling lipid with multifunctional properties. PA functions in the membrane through the interaction of its negatively charged phosphomonoester headgroup with positively charged proteins and ions. DGPP, like PA, can interact electrostatically via the electrostatic-hydrogen bond switch mechanism but differs from PA in its overall charge and shape. The formation of DGPP from PA alters the physicochemical properties as well as the structural dynamics of the membrane. This potentially impacts the molecular and ionic binding of cationic proteins and ions with the DGPP enriched membrane. However, the results of these important interactions in the stress response and in DGPP's overall intracellular function is unknown. Here, using P MAS NMR, we analyze the effect of the interaction of low DGPP concentrations in model membranes with the peptides KALP23 and WALP23, which are flanked by positively charged Lysine and neutral Tryptophan residues, respectively. Our results show a significant effect of KALP23 on the charge of DGPP as compared to WALP23. There was, however, no significant effect on the charge of the phosphomonoester of DGPP due to the interaction with positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and dioleoyl ethyl-phosphatidylcholine (EtPC). Divalent calcium and magnesium cations induce deprotonation of the DGPP headgroup but showed no noticeable differences on DGPP's charge. Our results lead to a novel model for DGPP-protein interaction.
Topics: Cations, Divalent; Diphosphates; Glycerol; Lysine; Magnetic Resonance Spectroscopy; Models, Molecular; Peptides; Phosphatidylcholines; Proteins; Static Electricity
PubMed: 35053406
DOI: 10.3390/cells11020290 -
Best Practice & Research. Clinical... Dec 2021Osteoarthritis (OA) is a degenerative joint disease characterized by progressive degeneration of articular cartilage. Due to its high prevalence and limited treatment... (Review)
Review
Osteoarthritis (OA) is a degenerative joint disease characterized by progressive degeneration of articular cartilage. Due to its high prevalence and limited treatment options, OA has become one of the most disabling diseases in developed countries. In recent years, OA has been recognized as a heterogenic disease with various phenotypes. Calcium crystal-related endotypes, which are defined by either a distinct functional or pathobiological mechanism, are present in approximately 60% of all OA patients. Two different calcium crystals can accumulate in the joint and thereby calcify the cartilage matrix, which are basic calcium phosphate (BCP) and calcium pyrophosphate (CPP) crystals. The formation of these crystals depends mainly on the balance of phosphate and pyrophosphate, which is regulated by specific proteins controlling the pyrophosphate metabolism. Dysregulation of these molecules subsequently leads to preferential formation of either BCP or CPP crystals. BCP crystals, on the one hand, are directly associated with OA severity and cartilage degradation. They are mostly located in the deeper cartilage layers and are associated with chondrocyte hypertrophy. CPP crystal deposition, on the other hand, is a hallmark of chondrocalcinosis and is associated with aging and chondrocyte senescence. Therefore, BCP and CPP crystals are associated with different chondrocyte phenotypes. However, BCP and CPP crystals are not mutually exclusive and can coexist in OA, creating a mixed endotype of OA. Both crystals clearly play a role in the pathogenesis of OA. However, the exact impact of each crystal type on either driving the disease progression or being a result of chondrocyte differentiation is still to be elucidated.
Topics: Calcium; Calcium Pyrophosphate; Cartilage, Articular; Chondrocalcinosis; Chondrocytes; Humans; Osteoarthritis
PubMed: 34732285
DOI: 10.1016/j.berh.2021.101722 -
PLoS Pathogens May 2021Bacteria inhabit diverse environmental niches and consequently must modulate their metabolism to adapt to stress. The nucleotide second messengers guanosine... (Review)
Review
Bacteria inhabit diverse environmental niches and consequently must modulate their metabolism to adapt to stress. The nucleotide second messengers guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) (collectively referred to as (p)ppGpp) are essential for survival during nutrient starvation. (p)ppGpp is synthesized by the RelA-SpoT homologue (RSH) protein family and coordinates the control of cellular metabolism through its combined effect on over 50 proteins. While the role of (p)ppGpp has largely been associated with nutrient limitation, recent studies have shown that (p)ppGpp and related nucleotides have a previously underappreciated effect on different aspects of bacterial physiology, such as maintaining cellular homeostasis and regulating bacterial interactions with a host, other bacteria, or phages. (p)ppGpp produced by pathogenic bacteria facilitates the evasion of host defenses such as reactive nitrogen intermediates, acidic pH, and the complement system. Additionally, (p)ppGpp and pyrophosphorylated derivatives of canonical adenosine nucleotides called (p)ppApp are emerging as effectors of bacterial toxin proteins. Here, we review the RSH protein family with a focus on its unconventional roles during host infection and bacterial competition.
Topics: Animals; Bacteria; Bacterial Infections; Bacterial Physiological Phenomena; Bacterial Proteins; Diphosphates; Gene Expression Regulation, Bacterial; Humans; Nucleotides; Phosphorylation; Stress, Physiological
PubMed: 33984072
DOI: 10.1371/journal.ppat.1009532 -
Journal of Dental Research Jun 2021Biomineralization is regulated by inorganic pyrophosphate (PP), a potent physiological inhibitor of hydroxyapatite crystal growth. Progressive ankylosis protein (ANK)...
Biomineralization is regulated by inorganic pyrophosphate (PP), a potent physiological inhibitor of hydroxyapatite crystal growth. Progressive ankylosis protein (ANK) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) act to increase local extracellular levels of PP, inhibiting mineralization. The periodontal complex includes 2 mineralized tissues, cementum and alveolar bone (AB), both essential for tooth attachment. Previous studies demonstrated that loss of function of ANK or ENPP1 (reducing PP) resulted in increased cementum formation, suggesting PP metabolism may be a target for periodontal regenerative therapies. To compare the effects of genetic ablation of , and both factors concurrently on cementum and AB regeneration, mandibular fenestration defects were created in knockout ( KO), mutant (), and double KO (dKO) mice. Genetic ablation of , or both factors increased cementum regeneration compared to controls at postoperative days (PODs) 15 and 30 ( KO: 8-fold, 3-fold; : 7-fold, 3-fold; dKO: 11-fold, 4-fold, respectively) associated with increased fluorochrome labeling and expression of mineralized tissue markers, dentin matrix protein 1 (/DMP1), osteopontin (/OPN), and bone sialoprotein (/BSP). Furthermore, dKO mice featured increased cementum thickness compared to single KOs at POD15 and KO at POD30. No differences were noted in AB volume between genotypes, but osteoblast/osteocyte markers were increased in all KOs, partially mineralized osteoid volume was increased in dKO versus controls at POD15 (3-fold), and mineral density was decreased in and dKOs at POD30 (6% and 9%, respectively). Increased numbers of osteoclasts were present in regenerated AB of all KOs versus controls. These preclinical studies suggest PP modulation as a potential and novel approach for cementum regeneration, particularly targeting ENPP1 and/or ANK. Differences in cementum and AB regeneration in response to reduced PP conditions highlight the need to consider tissue-specific responses in strategies targeting regeneration of the entire periodontal complex.
Topics: Animals; Bone and Bones; Dental Cementum; Diphosphates; Mice; Mice, Knockout; Tooth; Tooth Ankylosis
PubMed: 33356859
DOI: 10.1177/0022034520981854 -
Journal of Nuclear Cardiology :... Jun 2023
Topics: Humans; Artifacts; Technetium Tc 99m Pyrophosphate; Diagnostic Imaging
PubMed: 35277832
DOI: 10.1007/s12350-022-02929-2 -
Journal of Nuclear Cardiology :... Oct 2022
Topics: Diphosphates; Heart; Humans; Technetium; Technetium Tc 99m Pyrophosphate
PubMed: 33409892
DOI: 10.1007/s12350-020-02498-2 -
Biomolecules Jun 2022Ribonucleotide reductase (RR) is an essential multi-subunit enzyme found in all living organisms; it catalyzes the rate-limiting step in dNTP synthesis, namely, the... (Review)
Review
Ribonucleotide reductase (RR) is an essential multi-subunit enzyme found in all living organisms; it catalyzes the rate-limiting step in dNTP synthesis, namely, the conversion of ribonucleoside diphosphates to deoxyribonucleoside diphosphates. As expression levels of human RR (hRR) are high during cell replication, hRR has long been considered an attractive drug target for a range of proliferative diseases, including cancer. While there are many excellent reviews regarding the structure, function, and clinical importance of hRR, recent years have seen an increase in novel approaches to inhibiting hRR that merit an updated discussion of the existing inhibitors and strategies to target this enzyme. In this review, we discuss the mechanisms and clinical applications of classic nucleoside analog inhibitors of hRRM1 (large catalytic subunit), including gemcitabine and clofarabine, as well as inhibitors of the hRRM2 (free radical housing small subunit), including triapine and hydroxyurea. Additionally, we discuss novel approaches to targeting RR and the discovery of new classes of hRR inhibitors.
Topics: Catalytic Domain; Diphosphates; Enzyme Inhibitors; Humans; Neoplasms; Ribonucleotide Reductases
PubMed: 35740940
DOI: 10.3390/biom12060815