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Biosynthesis

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https://www.readbyqxmd.com/read/29786941/a-regio-and-diastereoselective-anodic-aryl-aryl-coupling-in-the-biomimetic-total-synthesis-of-thebaine
#1
Alexander Lipp, Dorota Ferenc, Christoph Gütz, Mario Geffe, Nina Vierengel, Dieter Schollmeyer, Hans Jürgen Schäfer, Siegfried R Waldvogel, Till Opatz
The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)-reticuline. For decades, chemists have sought to mimic this coupling using stoichiometric oxidants. However, all approaches suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regioselective and diastereoselective anodic coupling of 3',4',5'-trioxygenated laudanosine derivatives is presented, which finally enabled an electrochemical access to (-)-thebaine...
May 22, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29786865/infection-with-phytopathogenic-bacterium-inhibits-melatonin-biosynthesis-decreases-longevity-of-its-vector-and-suppresses-the-free-radical-defense
#2
Yasser Nehela, Nabil Killiny
Vector-borne phytopathogenic bacteria may alter the reproductive fitness, survival, behavior, and metabolism of their vectors. Candidatus Liberibacter asiaticus (CLas) is associated with the Huanglongbing (HLB; also known as citrus greening disease), one of the most destructive citrus diseases worldwide, and transmitted by Asian citrus psyllid, Diaphorina citri (Insecta, Hemiptera, Liviidae). The genome sequencing of CLas revealed that it does not have the ability to synthesize tryptophan, the precursor of melatonin, and it must acquire it from its host plant or insect vector to achieve its biological processes, such as growth and multiplication...
May 22, 2018: Journal of Pineal Research
https://www.readbyqxmd.com/read/29786859/synergistic-effects-of-abiotic-stresses-in-plants-a-case-study-of-nitrogen-limitation-and-saturating-light-intensity-in-arabidopsis-thaliana
#3
Itay Cohen, Tal Rapaport, Vered Chalifa-Caspi, Shimon Rachmilevitch
Under natural conditions, plants are regularly exposed to combinations of stress factors. A common example is the conjunction between nitrogen (N) deficiency and excess light. The combined effect of stress factors is often ignored in studies using controlled conditions, possibly resulting in misleading conclusions. To address this issue, the current study examined the physiological behavior of Arabidopsis thaliana under the effect of varying nitrogen levels and light intensities. The joint influence of low N and excess light had an adverse effect on plant growth, chlorophyll and anthocyanin concentrations, photochemical capacity, and the abundance of proteins involved in carbon assimilation and anti-oxidative metabolism...
May 22, 2018: Physiologia Plantarum
https://www.readbyqxmd.com/read/29786761/engineering-terpenoid-production-through-transient-expression-in-nicotiana-benthamiana
#4
REVIEW
James Reed, Anne Osbourn
Terpenoids are the most structurally diverse class of plant natural products with a huge range of commercial and medical applications. Exploiting this enormous potential has historically been hindered due to low levels of these compounds in their natural sources, making isolation difficult, while their structural complexity frequently makes synthetic chemistry approaches uneconomical. Engineering terpenoid biosynthesis in heterologous host production platforms provides a means to overcome these obstacles. In particular, plant-based production systems are attractive as they provide the compartmentalisation and cofactors necessary for the transfer of functional pathways from other plants...
May 21, 2018: Plant Cell Reports
https://www.readbyqxmd.com/read/29786169/bangladeshi-children-with-acute-diarrhea-show-fecal-microbiomes-with-increased-streptococcus-abundance-irrespective-of-diarrhea-etiology
#5
Silas Kieser, Shafiqul A Sarker, Olga Sakwinska, Francis Foata, Shamima Sultana, Zeenat Khan, Shoheb Islam, Nadine Porta, Séverine Combremont, Bertrand Betrisey, Coralie Fournier, Aline Charpagne, Patrick Descombes, Annick Mercenier, Bernard Berger, Harald Brüssow
We report streptococcal dysbiosis in acute diarrhea irrespective of etiology. Compared to 20 healthy local controls, 71 Bangladeshi children hospitalized with acute diarrhea (AD) of viral, mixed viral/bacterial, bacterial and unknown etiology showed a significantly decreased bacterial diversity with loss of pathways characteristic for the healthy distal colon microbiome (mannan degradation, methylerythritol phosphate and thiamin biosynthesis), an increased proportion of fecal streptococci belonging to the Streptococcus bovis and Streptococcus salivarius species complexes, and an increased level of E...
May 22, 2018: Environmental Microbiology
https://www.readbyqxmd.com/read/29785900/insulin-suppresses-the-ampk-signaling-pathway-to-regulate-lipid-metabolism-in-primary-cultured-hepatocytes-of-dairy-cows
#6
Xinwei Li, Yu Li, Hongyan Ding, Jihong Dong, Renhe Zhang, Dan Huang, Lin Lei, Zhe Wang, Guowen Liu, Xiaobing Li
Dairy cows with type II ketosis display hepatic fat accumulation and hyperinsulinemia, but the underlying mechanism is not completely clear. This study aimed to clarify the regulation of lipid metabolism by insulin in cow hepatocytes. In vitro, cow hepatocytes were treated with 0, 1, 10, or 100 nm insulin in the presence or absence of AICAR (an AMP-activated protein kinase alpha (AMPKα) activator). The results showed that insulin decreased AMPKα phosphorylation. This inactivation of AMPKα increased the gene and protein expression levels of carbohydrate responsive element-binding protein (ChREBP) and sterol regulatory element-binding protein-1c (SREBP-1c), which downregulated the expression of lipogenic genes, thereby decreasing lipid biosynthesis...
May 2018: Journal of Dairy Research
https://www.readbyqxmd.com/read/29785852/syntheses-of-gibberellins-a-15-and-a-24-the-key-metabolites-in-gibberellin-biosynthesis
#7
David J-Y D Bon, Lewis Norman Mander, Ping Lan
Gibberellins (GAs) are essential phytohormones involved in numerous aspects of plant growth and development. Notably, the biochemistry and genetics of GA biosynthesis which is associated with their endogenous regulation has been largely resolved, however, a crucial unsolved question remains: the precise mechanism of the stepwise oxidation and subsequent removal of C-20 from C20-precursors leading to bioactive C19 gibberellins is still unresolved. In order to satisfy numerous requests from biologists, practical preparations of certain GAs that were isolated in miniscule quantities are highly demanded...
May 22, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29785628/gut-associated-bacteria-of-helicoverpa-zea-indirectly-trigger-plant-defenses-in-maize
#8
Jie Wang, Mingyu Yang, Yuanyuan Song, Flor E Acevedo, Kelli Hoover, Rensen Zeng, Gary W Felton
Insect-associated microbes can contribute to the physiological and ecological functions of insects. Despite a few examples in beetles and piercing-sucking insects, the varied mechanisms of how insect-associated bacteria mediate plant-insect interactions are still not fully understood. The polyphagous herbivore Helicoverpa zea is a major agricultural pest that harbors certain microbes in their digestive systems. Enterobacter ludwigii is one of the gut-associated bacteria identified from field-collected caterpillars, and it has been shown to indirectly induce defenses in the dicot plant tomato by triggering the biosynthesis of salivary elicitors, but there are no clear mechanisms to show how gut microbes alter these salivary cues and how a different host plant responds to these inducible elicitors...
May 22, 2018: Journal of Chemical Ecology
https://www.readbyqxmd.com/read/29785497/crystal-structure-of-arabidopsis-thaliana-glutamyl-trna-glu-reductase-in-complex-with-nadph-and-glutamyl-trna-glu-reductase-binding-protein
#9
Aiguo Zhao, Feng Han
In higher plants, the tetrapyrrole biosynthesis pathway starts from the reaction catalyzed by the rate-limiting enzyme, glutamyl-tRNAGlu reductase (GTR). In Arabidopsis thaliana, GTR is controlled by post-transcriptional regulators such as GTR binding protein (GBP), which stimulates AtGTR activity. The NADPH-binding domain of AtGTR undergoes a substantial movement upon GBP binding. Here, we report the crystal structure of AtGTR-NADPH-GBP ternary complex. NADPH binding causes slight structural changes compared with the AtGTR-GBP binary complex, and possibly take a part of the space needed by the substrate glutamyl-tRNAGlu ...
May 21, 2018: Photosynthesis Research
https://www.readbyqxmd.com/read/29784878/oxidative-decarboxylation-of-pyruvate-by-1-deoxy-d-xyulose-5-phosphate-synthase-a-central-metabolic-enzyme-in-bacteria
#10
Alicia A DeColli, Natasha S Nemeria, Ananya Majumdar, Gary J Gerfen, Frank Jordan, Caren L Freel Meyers
The underexploited antibacterial target 1-deoxy-D-xyluose 5-phosphate (DXP) synthase, catalyzes the thiamin diphosphate (ThDP)-dependent formation of DXP from pyruvate and D-glyceraldehyde 3-phosphate (D-GAP). DXP is an essential intermediate in the biosynthesis of ThDP, pyridoxal phosphate, and isoprenoids in many pathogenic bacteria. DXP synthase catalyzes a distinct mechanism in ThDP decarboxylative enzymology in which the first enzyme-bound pre-decarboxylation intermediate, C2α-lactylThDP (LThDP), is stabilized by DXP synthase in the absence of D-GAP, and D-GAP then induces efficient LThDP decarboxylation...
May 21, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29784821/characterization-of-gossypol-biosynthetic-pathway
#11
Xiu Tian, Ju-Xin Ruan, Jin-Quan Huang, Chang-Qing Yang, Xin Fang, Zhi-Wen Chen, Hui Hong, Ling-Jian Wang, Ying-Bo Mao, Shan Lu, Tian-Zhen Zhang, Xiao-Ya Chen
Gossypol and related sesquiterpene aldehydes in cotton function as defense compounds but are antinutritional in cottonseed products. By transcriptome comparison and coexpression analyses, we identified 146 candidates linked to gossypol biosynthesis. Analysis of metabolites accumulated in plants subjected to virus-induced gene silencing (VIGS) led to the identification of four enzymes and their supposed substrates. In vitro enzymatic assay and reconstitution in tobacco leaves elucidated a series of oxidative reactions of the gossypol biosynthesis pathway...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29784804/structure-of-xyloglucan-xylosyltransferase-1-reveals-simple-steric-rules-that-define-biological-patterns-of-xyloglucan-polymers
#12
Alan T Culbertson, Jacqueline J Ehrlich, Jun-Yong Choe, Richard B Honzatko, Olga A Zabotina
The plant cell wall is primarily a polysaccharide mesh of the most abundant biopolymers on earth. Although one of the richest sources of biorenewable materials, the biosynthesis of the plant polysaccharides is poorly understood. Structures of many essential plant glycosyltransferases are unknown and suitable substrates are often unavailable for in vitro analysis. The dearth of such information impedes the development of plants better suited for industrial applications. Presented here are structures of Arabidopsis xyloglucan xylosyltransferase 1 (XXT1) without ligands and in complexes with UDP and cellohexaose...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29784782/riboswitches-for-the-alarmone-ppgpp-expand-the-collection-of-rna-based-signaling-systems
#13
Madeline E Sherlock, Narasimhan Sudarsan, Ronald R Breaker
Riboswitches are noncoding portions of certain mRNAs that bind metabolite, coenzyme, signaling molecule, or inorganic ion ligands and regulate gene expression. Most known riboswitches sense derivatives of RNA monomers. This bias in ligand chemical composition is consistent with the hypothesis that widespread riboswitch classes first emerged during the RNA World, which is proposed to have existed before proteins were present. Here we report the discovery and biochemical validation of a natural riboswitch class that selectively binds guanosine tetraphosphate (ppGpp), a widespread signaling molecule and bacterial "alarmone" derived from the ribonucleotide GTP...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29784775/recombinant-escherichia-coli-as-a-biofactory-for-various-single-and-multi-element-nanomaterials
#14
Yoojin Choi, Tae Jung Park, Doh C Lee, Sang Yup Lee
Nanomaterials (NMs) are mostly synthesized by chemical and physical methods, but biological synthesis is also receiving great attention. However, the mechanisms for biological producibility of NMs, crystalline versus amorphous, are not yet understood. Here we report biosynthesis of 60 different NMs by employing a recombinant Escherichia coli strain coexpressing metallothionein, a metal-binding protein, and phytochelatin synthase that synthesizes a metal-binding peptide phytochelatin. Both an in vivo method employing live cells and an in vitro method employing the cell extract are used to synthesize NMs...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29784770/tlr-activated-repression-of-fe-s-cluster-biogenesis-drives-a-metabolic-shift-and-alters-histone-and-tubulin-acetylation
#15
Wing-Hang Tong, Nunziata Maio, De-Liang Zhang, Erika M Palmieri, Hayden Ollivierre, Manik C Ghosh, Daniel W McVicar, Tracey A Rouault
Given the essential roles of iron-sulfur (Fe-S) cofactors in mediating electron transfer in the mitochondrial respiratory chain and supporting heme biosynthesis, mitochondrial dysfunction is a common feature in a growing list of human Fe-S cluster biogenesis disorders, including Friedreich ataxia and GLRX5-related sideroblastic anemia. Here, our studies showed that restriction of Fe-S cluster biogenesis not only compromised mitochondrial oxidative metabolism but also resulted in decreased overall histone acetylation and increased H3K9me3 levels in the nucleus and increased acetylation of α-tubulin in the cytosol by decreasing the lipoylation of the pyruvate dehydrogenase complex, decreasing levels of succinate dehydrogenase and the histone acetyltransferase ELP3, and increasing levels of the tubulin acetyltransferase MEC17...
May 22, 2018: Blood Advances
https://www.readbyqxmd.com/read/29784422/development-of-a-sers-strategy-to-overcome-the-nanoparticle-stabilisation-effect-in-serum-containing-samples-application-to-the-quantification-of-dopamine-in-the-culture-medium-of-pc-12-cells
#16
E Dumont, C De Bleye, J Cailletaud, P-Y Sacré, P-B Van Lerberghe, B Rogister, G A Rance, J W Aylott, Ph Hubert, E Ziemons
The analysis of serum samples by surface-enhanced Raman spectroscopy (SERS) has gained ground over the last few years. However, the stabilisation of colloids by the proteins contained in these samples has restricted their use in common practice, unless antibodies or aptamers are used. Therefore, this work was dedicated to the development of a SERS methodology allowing the analysis of serum samples in a simple and easy-to-implement way. This approach was based on the pre-aggregation of the colloid with a salt solution...
August 15, 2018: Talanta
https://www.readbyqxmd.com/read/29783748/neuronal-dysfunction-associated-with-cholesterol-deregulation
#17
Annalisa Marcuzzi, Claudia Loganes, Erica Valencic, Elisa Piscianz, Lorenzo Monasta, Sabrine Bilel, Roberta Bortul, Claudio Celeghini, Marina Zweyer, Alberto Tommasini
Cholesterol metabolism is crucial for cells and, in particular, its biosynthesis in the central nervous system occurs in situ, and its deregulation involves morphological changes that cause functional variations and trigger programmed cell death. The pathogenesis of rare diseases, such as Mevalonate Kinase Deficiency or Smith⁻Lemli⁻Opitz Syndrome, arises due to enzymatic defects in the cholesterol metabolic pathways, resulting in a shortage of downstream products. The most severe clinical manifestations of these diseases appear as neurological defects...
May 19, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29783739/sterol-composition-of-clinically-relevant-mucorales-and-changes-resulting-from-posaconazole-treatment
#18
Christoph Müller, Thomas Neugebauer, Patrizia Zill, Cornelia Lass-Flörl, Franz Bracher, Ulrike Binder
Mucorales are fungi with increasing importance in the clinics. Infections take a rapidly progressive course resulting in high mortality rates. The ergosterol biosynthesis pathway and sterol composition are of interest, since they are targeted by currently applied antifungal drugs. Nevertheless, Mucorales often exhibit resistance to these drugs, resulting in therapeutic failure. Here, sterol patterns of six clinically relevant Mucorales ( Lichtheimia corymbifera , Lichtheimia ramosa , Mucor circinelloides , Rhizomucor pusillus , Rhizopus arrhizus , and Rhizopus microsporus ) were analysed in a targeted metabolomics fashion after derivatization by gas chromatography-mass spectrometry...
May 19, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29783733/improved-synthesis-of-n-methylcadaverine
#19
Kayla N Anderson, Shiva Moaven, Daniel K Unruh, Anthony F Cozzolino, John C D'Auria
Alkaloids compose a large class of natural products, and mono-methylated polyamines are a common intermediate in their biosynthesis. In order to evaluate the role of selectively methylated natural products, synthetic strategies are needed to prepare them. Here, N -methylcadaverine is prepared in 37.3% yield in three steps. The alternative literature two-step strategy resulted in reductive deamination to give N -methylpiperidine as determined by the single crystal structure. A straightforward strategy to obtain the mono-alkylated aliphatic diamine, cadaverine, which avoids potential side-reactions, is demonstrated...
May 19, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29783672/synergistic-viral-replication-of-marek-s-disease-virus-and-avian-leukosis-virus-subgroup-j-is-responsible-for-the-enhanced-pathogenicity-in-the-superinfection-of-chickens
#20
Jing Zhou, Guo-Liang Zhao, Xiao-Man Wang, Xu-Sheng Du, Shuai Su, Chen-Gui Li, Venugopal Nair, Yong-Xiu Yao, Zi-Qiang Cheng
Superinfection of Marek's disease virus (MDV) and avian leukosis virus subgroup J (ALV-J) causes lethal neoplasia and death in chickens. However, whether there is synergism between the two viruses in viral replication and pathogenicity has remained elusive. In this study, we found that the superinfection of MDV and ALV-J increased the viral replication of the two viruses in RNA and protein level, and synergistically promoted the expression of IL-10, IL-6, and TGF-β in chicken embryo fibroblasts (CEF). Moreover, MDV and ALV-J protein expression in dual-infected cells detected by confocal laser scanning microscope appeared earlier in the cytoplasm and the nucleus, and caused more severe cytopathy than single infection, suggesting that synergistically increased MDV and ALV-J viral-protein biosynthesis is responsible for the severe cytopathy...
May 18, 2018: Viruses
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