Source of 12C in Calvin–Benson cycle intermediates and isoprene emitted from plant leaves fed with 13CO2

Feeding 14CO2 was crucial to uncovering the path of carbon in photosynthesis. Feeding 13CO2 to photosynthesizing leaves emitting isoprene has been used to develop hypotheses about the sources of carbon for the methylerythritol 4-phosphate pathway, which makes the precursors for terpene synthesis in chloroplasts and bacteria. Both photosynthesis and isoprene studies found that products label very quickly (<10 min) up to 80–90% but the last 10–20% of labeling requires hours indicating a source of 12C during photosynthesis and isoprene emission. Furthermore, studies with isoprene showed that the proportion of slow label could vary significantly. This was interpreted as a variable contribution of carbon from sources other than the Calvin–Benson cycle (CBC) feeding the methylerythritol 4-phosphate pathway. Here, we measured the degree of label in isoprene and photosynthetic metabolites 20 min after beginning to feed 13CO2. Isoprene labeling was the same as labeling of photosynthesis intermediates. High temperature reduced the label in isoprene and photosynthesis intermediates by the same amount indicating no role for alternative carbon sources for isoprene. A model assuming glucose, fructose, and/or sucrose reenters the CBC as ribulose 5-phosphate through a cytosolic shunt involving glucose 6-phosphate dehydrogenase was consistent with the observations.

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Simultaneous Catabolite Repression between Glucose and Toluene Metabolism in Pseudomonas putida Is Channeled through Different Signaling Pathways

Journal of Bacteriology ◽

10.1128/jb.00679-07 ◽

2007 ◽

Vol 189 (18) ◽

pp. 6602-6610 ◽

Cited By ~ 75

Author(s):

Teresa del Castillo ◽

Juan L. Ramos

Keyword(s):

Glucose Metabolism ◽

Pseudomonas Putida ◽

Catabolite Repression ◽

Carbon Sources ◽

Flux Analysis ◽

Glucose Determination ◽

Net Flux ◽

Glucose 6 Phosphate Dehydrogenase ◽

Metabolism Gene

ABSTRACT Pseudomonas putida KT2440(pWW0) can use toluene via the TOL plasmid-encoded catabolic pathways and can use glucose via a series of three peripheral chromosome-encoded routes that convert glucose into 6-phosphogluconate (6PG), namely, the glucokinase pathway, in which glucose is transformed to 6PG through the action of glucokinase and glucose-6-phosphate dehydrogenase. Alternatively, glucose can be oxidized to gluconate, which can be phosphorylated by gluconokinase to 6PG or oxidized to 2-ketogluconate, which, in turn, is converted into 6PG. Our results show that KT2440 metabolizes glucose and toluene simultaneously, as revealed by net flux analysis of [13C]glucose. Determination of glucokinase and gluconokinase activities in glucose metabolism, gene expression assays using a fusion of the promoter of the Pu TOL upper pathway to ′lacZ, and global transcriptomic assays revealed simultaneous catabolite repression in the use of these two carbon sources. The effect of toluene on glucose metabolism was directed to the glucokinase branch and did not affect gluconate metabolism. Catabolite repression of the glucokinase pathway and the TOL pathway was triggered by two different catabolite repression systems. Expression from Pu was repressed mainly via PtsN in response to high levels of 2-dehydro-3-deoxygluconate-6-phosphate, whereas repression of the glucokinase pathway was channeled through Crc.

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RNAi-mediated suppression of isoprene emission in poplar transiently impacts phenolic metabolism under high temperature and high light intensities: a transcriptomic and metabolomic analysis

Plant Molecular Biology ◽

10.1007/s11103-010-9654-z ◽

2010 ◽

Vol 74 (1-2) ◽

pp. 61-75 ◽

Cited By ~ 36

Author(s):

Katja Behnke ◽

Andreas Kaiser ◽

Ina Zimmer ◽

Nicolas Brüggemann ◽

Dennis Janz ◽

...

Keyword(s):

High Temperature ◽

High Light ◽

Metabolomic Analysis ◽

Phenolic Metabolism ◽

Isoprene Emission ◽

Light Intensities

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Kluyveromyces marxianus: Current State of Omics Studies, Strain Improvement Strategy and Potential Industrial Implementation

Fermentation ◽

10.3390/fermentation6040124 ◽

2020 ◽

Vol 6 (4) ◽

pp. 124

Author(s):

Dung Minh Ha-Tran ◽

Trinh Thi My Nguyen ◽

Chieh-Chen Huang

Keyword(s):

High Temperature ◽

Ethanol Production ◽

Kluyveromyces Marxianus ◽

Plant Biomass ◽

High Titer ◽

Carbon Sources ◽

Strain Improvement ◽

Improvement Strategy ◽

Yeast Saccharomyces Cerevisiae ◽

Wide Range

Bioethanol is considered an excellent alternative to fossil fuels, since it importantly contributes to the reduced consumption of crude oil, and to the alleviation of environmental pollution. Up to now, the baker yeast Saccharomyces cerevisiae is the most common eukaryotic microorganism used in ethanol production. The inability of S. cerevisiae to grow on pentoses, however, hinders its effective growth on plant biomass hydrolysates, which contain large amounts of C5 and C12 sugars. The industrial-scale bioprocessing requires high temperature bioreactors, diverse carbon sources, and the high titer production of volatile compounds. These criteria indicate that the search for alternative microbes possessing useful traits that meet the required standards of bioethanol production is necessary. Compared to other yeasts, Kluyveromyces marxianus has several advantages over others, e.g., it could grow on a broad spectrum of substrates (C5, C6 and C12 sugars); tolerate high temperature, toxins, and a wide range of pH values; and produce volatile short-chain ester. K. marxianus also shows a high ethanol production rate at high temperature and is a Crabtree-negative species. These attributes make K. marxianus promising as an industrial host for the biosynthesis of biofuels and other valuable chemicals.

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Deletion of the Glucose-6-Phosphate Dehydrogenase Gene KlZWF1 Affects both Fermentative and Respiratory Metabolism in Kluyveromyces lactis

Eukaryotic Cell ◽

10.1128/ec.00189-06 ◽

2006 ◽

Vol 6 (1) ◽

pp. 19-27 ◽

Cited By ~ 17

Author(s):

Michele Saliola ◽

Gina Scappucci ◽

Ilaria De Maria ◽

Tiziana Lodi ◽

Patrizia Mancini ◽

...

Keyword(s):

Biomass Yield ◽

Kluyveromyces Lactis ◽

Carbon Sources ◽

Pentose Phosphate ◽

Respiratory Metabolism ◽

Wild Type ◽

Dehydrogenase Gene ◽

Increased Sensitivity ◽

Dimeric Form ◽

Glucose 6 Phosphate Dehydrogenase

ABSTRACT In Kluyveromyces lactis, the pentose phosphate pathway is an alternative route for the dissimilation of glucose. The first enzyme of the pathway is the glucose-6-phosphate dehydrogenase (G6PDH), encoded by KlZWF1. We isolated this gene and examined its role. Like ZWF1 of Saccharomyces cerevisiae, KlZWF1 was constitutively expressed, and its deletion led to increased sensitivity to hydrogen peroxide on glucose, but unlike the case for S. cerevisiae, the Klzwf1Δ strain had a reduced biomass yield on fermentative carbon sources as well as on lactate and glycerol. In addition, the reduced yield on glucose was associated with low ethanol production and decreased oxygen consumption, indicating that this gene is required for both fermentation and respiration. On ethanol, however, the mutant showed an increased biomass yield. Moreover, on this substrate, wild-type cells showed an additional band of activity that might correspond to a dimeric form of G6PDH. The partial dimerization of the G6PDH tetramer on ethanol suggested the production of an NADPH excess that was negative for biomass yield.

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Hafnium Reactivity with Boron and Carbon Sources Under Non-Self-Propagating High-Temperature Synthesis Conditions

Journal of the American Ceramic Society ◽

10.1111/j.1551-2916.2008.02329.x ◽

2008 ◽

Vol 91 (5) ◽

pp. 1481-1488 ◽

Cited By ~ 28

Author(s):

Yigal D. Blum ◽

Jochen Marschall ◽

David Hui ◽

Brian Adair ◽

Michael Vestel

Keyword(s):

High Temperature ◽

Carbon Sources ◽

Temperature Synthesis ◽

Synthesis Conditions ◽

High Temperature Synthesis

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Crc Is Involved in Catabolite Repression Control of the bkd Operons of Pseudomonas putida andPseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.182.4.1144-1149.2000 ◽

2000 ◽

Vol 182 (4) ◽

pp. 1144-1149 ◽

Cited By ~ 85

Author(s):

Kathryn L. Hester ◽

Jodi Lehman ◽

Fares Najar ◽

Lin Song ◽

Bruce A. Roe ◽

...

Keyword(s):

Pseudomonas Putida ◽

Catabolite Repression ◽

Carbon Sources ◽

Keto Acid ◽

Carbon Regulation ◽

Acid Dehydrogenase ◽

Transposon Mutants ◽

Branched Chain ◽

Glucose 6 Phosphate Dehydrogenase

ABSTRACT Crc (catabolite repression control) protein of Pseudomonas aeruginosa has shown to be involved in carbon regulation of several pathways. In this study, the role of Crc in catabolite repression control has been studied in Pseudomonas putida. The bkd operons of P. putida and P. aeruginosa encode the inducible multienzyme complex branched-chain keto acid dehydrogenase, which is regulated in both species by catabolite repression. We report here that this effect is mediated in both species by Crc. A 13-kb cloned DNA fragment containing the P. putida crc gene region was sequenced. Crc regulates the expression of branched-chain keto acid dehydrogenase, glucose-6-phosphate dehydrogenase, and amidase in both species but not urocanase, although the carbon sources responsible for catabolite repression in the two species differ. Transposon mutants affected in their expression of BkdR, the transcriptional activator of thebkd operon, were isolated and identified as crcand vacB (rnr) mutants. These mutants suggested that catabolite repression in pseudomonads might, in part, involve control of BkdR levels.

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