Thermococcus profundus 2-Ketoisovalerate Ferredoxin Oxidoreductase, a Key Enzyme in the Archaeal Energy-Producing Amino Acid Metabolic Pathway

2005 ◽  
Vol 137 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Y. Ozawa
Keyword(s):  
Amino Acid ◽  
Metabolic Pathway ◽  
Ferredoxin Oxidoreductase ◽  
Key Enzyme

scholarly journals Branched-chain amino acids sustain pancreatic cancer growth by regulating lipid metabolism

2019 ◽  
Vol 51 (11) ◽  
pp. 1-11 ◽  
Author(s):  
Ji Hyeon Lee ◽  
Young-ra Cho ◽  
Ji Hye Kim ◽  
Jongwook Kim ◽  
Hae Yun Nam ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Proliferation ◽  
Fatty Acid ◽  
Amino Acid ◽  
Metabolic Pathway ◽  
Cancer Growth ◽  
Pdac Cell ◽  
Growth And Survival ◽  
Branched Chain Amino Acid ◽  
Branched Chain

AbstractBranched-chain amino acid (BCAA) catabolism and high levels of enzymes in the BCAA metabolic pathway have recently been shown to be associated with cancer growth and survival. However, the precise roles of BCAA metabolism in cancer growth and survival remain largely unclear. Here, we found that BCAA metabolism has an important role in human pancreatic ductal adenocarcinoma (PDAC) growth by regulating lipogenesis. Compared with nontransformed human pancreatic ductal (HPDE) cells, PDAC cells exhibited significantly elevated BCAA uptake through solute carrier transporters, which were highly upregulated in pancreatic tumor tissues compared with normal tissues. Branched-chain amino-acid transaminase 2 (BCAT2) knockdown markedly impaired PDAC cell proliferation, but not HPDE cell proliferation, without significant alterations in glutamate or reactive oxygen species levels. Furthermore, PDAC cell proliferation, but not HPDE cell proliferation, was substantially inhibited upon knockdown of branched-chain α-keto acid dehydrogenase a (BCKDHA). Interestingly, BCKDHA knockdown had no significant effect on mitochondrial metabolism; that is, neither the level of tricarboxylic acid cycle intermediates nor the oxygen consumption rate was affected. However, BCKDHA knockdown significantly inhibited fatty-acid synthesis, indicating that PDAC cells may utilize BCAAs as a carbon source for fatty-acid biosynthesis. Overall, our findings show that the BCAA metabolic pathway may provide a novel therapeutic target for pancreatic cancer.

scholarly journals Molecular Analysis of the Rebeccamycin l-Amino Acid Oxidase from Lechevalieria aerocolonigenes ATCC 39243

2005 ◽  
Vol 187 (6) ◽  
pp. 2084-2092 ◽  
Author(s):  
Tomoyasu Nishizawa ◽  
Courtney C. Aldrich ◽  
David H. Sherman
Keyword(s):  
Amino Acid ◽  
Biochemical Characterization ◽  
Kinetic Studies ◽  
Biochemical Properties ◽  
Protein Product ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Left Hand ◽  
Key Enzyme ◽  
Hand Region

ABSTRACT Rebeccamycin, a member of the tryptophan-derived indolocarbazole family, is produced by Lechevalieria aerocolonigenes ATCC 39243. The biosynthetic pathway that specifies biosynthesis of this important metabolite is comprised of 11 genes spanning 18 kb of DNA. A presumed early enzyme involved in elaboration of the rebeccamycin aglycone is encoded by rebO, located at the left-hand region of the reb gene cluster. The deduced protein product, RebO (51.9 kDa), is an l-amino acid oxidase (l-AAO) that has 27% identity to an l-AAO from Scomber japonicus (animal, mackerel) and is a member of the family of FAD-dependent oxidase enzymes. In order to study the biochemical properties of this key enzyme, the rebO gene was overexpressed and purified from Escherichia coli. Biochemical characterization showed that RebO is dimeric, with a molecular mass of approximately 101 kDa. Further analysis revealed that the enzyme contains a noncovalently bound FAD cofactor and is reoxidized at the expense of molecular oxygen by producing one molecule of hydrogen peroxide. Based on kinetic studies, RebO shows significant preference for 7-chloro-l-tryptophan, suggesting its likely role as the natural early pathway substrate. Furthermore, the native RebO enzyme has evident, albeit limited, flexibility as shown by bioconversion studies with unnatural substrates. This work provides the first analysis of a structural enzyme involved in construction of this important class of indolocarbazole natural products.

scholarly journals Branched-chain amino acid aminotransferase 2 regulates ferroptotic cell death in cancer cells

2020 ◽  
Author(s):  
Kang Wang ◽  
Zhengyang Zhang ◽  
Hsiang-i Tsai ◽  
Yanfang Liu ◽  
Jie Gao ◽  
...  
Keyword(s):  
Cell Death ◽  
Amino Acid ◽  
Cancer Cells ◽  
Ectopic Expression ◽  
Branched Chain Amino Acid ◽  
Pancreatic Cancer Cells ◽  
Key Enzyme ◽  
Branched Chain

Abstract Ferroptosis, a form of iron-dependent cell death driven by cellular metabolism and iron-dependent lipid peroxidation, has been implicated as a tumor-suppressor function for cancer therapy. Recent advance revealed that the sensitivity to ferroptosis is tightly linked to numerous biological processes, including metabolism of amino acid and the biosynthesis of glutathione. Here, by using a high-throughput CRISPR/Cas9-based genetic screen in HepG2 hepatocellular carcinoma cells to search for metabolic proteins inhibiting ferroptosis, we identified a branched-chain amino acid aminotransferase 2 (BCAT2) as a novel suppressor of ferroptosis. Mechanistically, ferroptosis inducers (erastin, sorafenib, and sulfasalazine) activated AMPK/SREBP1 signaling pathway through iron-dependent ferritinophagy, which in turn inhibited BCAT2 transcription. We further confirmed that BCAT2 as the key enzyme mediating the metabolism of sulfur amino acid, regulated intracellular glutamate level, whose activation by ectopic expression specifically antagonize system Xc– inhibition and protected liver and pancreatic cancer cells from ferroptosis in vitro and in vivo. On the contrary, direct inhibition of BCAT2 by RNA interference, or indirect inhibition by blocking system Xc– activity, triggers ferroptosis. Finally, our results demonstrate the synergistic effect of sorafenib and sulfasalazine in downregulating BCAT2 expression and dictating ferroptotic death, where BCAT2 can also be used to predict the responsiveness of cancer cells to ferroptosis-inducing therapies. Collectively, these findings identify a novel role of BCAT2 in ferroptosis, suggesting a potential therapeutic strategy for overcoming sorafenib resistance.

scholarly journals Purification, Characterization, and Cloning of a Eubacterial 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase, a Key Enzyme Involved in Biosynthesis of Terpenoids

1999 ◽  
Vol 181 (4) ◽  
pp. 1256-1263 ◽  
Author(s):  
Shunji Takahashi ◽  
Tomohisa Kuzuyama ◽  
Haruo Seto
Keyword(s):  
Amino Acid ◽  
Coenzyme A ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Ph Optimum ◽  
Hmg Coa Reductase ◽  
Apparent Homogeneity ◽  
Key Enzyme ◽  
Coa Reductase

ABSTRACT The eubacterial 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (EC 1.1.1.34 ) was purified 3,000-fold fromStreptomyces sp. strain CL190 to apparent homogeneity with an overall yield of 2.1%. The purification procedure consisted of (NH4)2SO4 precipitation, heat treatment and anion exchange, hydrophobic interaction, and affinity chromatographies. The molecular mass of the enzyme was estimated to be 41 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 100 to 105 kDa by gel filtration chromatography, suggesting that the enzyme is most likely to be a dimer. The enzyme showed a pH optimum of around 7.2, with apparent Km values of 62 μM for NADPH and 7.7 μM for HMG-CoA. A gene from CL190 responsible for HMG-CoA reductase was cloned by the colony hybridization method with an oligonucleotide probe synthesized on the basis of the N-terminal sequence of the purified enzyme. The amino acid sequence of the CL190 HMG-CoA reductase revealed several limited motifs which were highly conserved and common to the eucaryotic and archaebacterial enzymes. These sequence conservations suggest a strong evolutionary pressure to maintain amino acid residues at specific positions, indicating that the conserved motifs might play important roles in the structural conformation and/or catalytic properties of the enzyme.

TiO2 nanoparticles induced sugar impairments and metabolic pathway shift towards amino acid metabolism in wheat

2020 ◽  
Vol 399 ◽  
pp. 122982 ◽  
Author(s):  
Sónia Silva ◽  
Tiago P. Ribeiro ◽  
Conceição Santos ◽  
Diana C.G.A. Pinto ◽  
Artur M.S. Silva
Keyword(s):  
Amino Acid ◽  
Tio2 Nanoparticles ◽  
Metabolic Pathway ◽  
Amino Acid Metabolism ◽  
Acid Metabolism

6. Metabolic pathways and enzyme evolution

2020 ◽  
pp. 85-100
Author(s):  
Paul Engel
Keyword(s):  
Amino Acid ◽  
Metabolic Pathway ◽  
Metabolic Pathways ◽  
Building Blocks ◽  
Enzyme Evolution

‘Metabolic pathways and enzyme evolution’ focuses on metabolic pathways and enzyme evolution. Although a few enzymes catalyse a single isolated reaction, most are part of a team that catalyses a series of reactions in which each enzyme picks up its predecessor’s product, taking it a step further to create a metabolic pathway. This pathway may be to build up, say, an amino acid from simpler starting molecules, or conversely to break down food molecules to yield new chemical building blocks and sometimes also to trap useable energy. Life is the combined outcome of this seemingly logical enzyme teamwork.

scholarly journals The Nonphosphorylative Entner-Doudoroff Pathway in the Thermoacidophilic Euryarchaeon Picrophilus torridus Involves a Novel 2-Keto-3-Deoxygluconate- Specific Aldolase

2009 ◽  
Vol 192 (4) ◽  
pp. 964-974 ◽  
Author(s):  
Matthias Reher ◽  
Tobias Fuhrer ◽  
Michael Bott ◽  
Peter Schönheit
Keyword(s):  
Amino Acid ◽  
Catalytic Efficiency ◽  
Start Codon ◽  
Ionization Time ◽  
Cell Extracts ◽  
Translation Start ◽  
Picrophilus Torridus ◽  
Key Enzyme ◽  
Kdpg Aldolase

ABSTRACT The pathway of glucose degradation in the thermoacidophilic euryarchaeon Picrophilus torridus has been studied by in vivo labeling experiments and enzyme analyses. After growth of P. torridus in the presence of [1-13C]- and [3-13C]glucose, the label was found only in the C-1 and C-3 positions, respectively, of the proteinogenic amino acid alanine, indicating the exclusive operation of an Entner-Doudoroff (ED)-type pathway in vivo. Cell extracts of P. torridus contained all enzyme activities of a nonphosphorylative ED pathway, which were not induced by glucose. Two key enzymes, gluconate dehydratase (GAD) and a novel 2-keto-3-deoxygluconate (KDG)-specific aldolase (KDGA), were characterized. GAD is a homooctamer of 44-kDa subunits, encoded by Pto0485. KDG aldolase, KDGA, is a homotetramer of 32-kDa subunits. This enzyme was highly specific for KDG with up to 2,000-fold-higher catalytic efficiency compared to 2-keto-3-deoxy-6-phosphogluconate (KDPG) and thus differs from the bifunctional KDG/KDPG aldolase, KD(P)GA of crenarchaea catalyzing the conversion of both KDG and KDPG with a preference for KDPG. The KDGA-encoding gene, kdgA, was identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) as Pto1279, and the correct translation start codon, an ATG 24 bp upstream of the annotated start codon of Pto1279, was determined by N-terminal amino acid analysis. The kdgA gene was functionally overexpressed in Escherichia coli. Phylogenetic analysis revealed that KDGA is only distantly related to KD(P)GA, both enzymes forming separate families within the dihydrodipicolinate synthase superfamily. From the data we conclude that P. torridus degrades glucose via a strictly nonphosphorylative ED pathway with a novel KDG-specific aldolase, thus excluding the operation of the branched ED pathway involving a bifunctional KD(P)GA as a key enzyme.

Sign in / Sign up

Export Citation Format

Share Document