scholarly journals Reductive tricarboxylic acid cycle enzymes and reductive amino acid synthesis pathways contribute to electron balance in a Rhodospirillum rubrum Calvin-cycle mutant

Microbiology ◽  
2020 ◽  
Vol 166 (2) ◽  
pp. 199-211 ◽  
Author(s):  
Alexandra L. McCully ◽  
Maureen C. Onyeziri ◽  
Breah LaSarre ◽  
Jennifer R. Gliessman ◽  
James B. McKinlay
Keyword(s):  
Amino Acid ◽  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Calvin Cycle ◽  
Acid Synthesis ◽  
Tricarboxylic Acid ◽  
Amino Acid Synthesis ◽  
Acid Cycle ◽  
Electron Balance ◽  
Reductive Tricarboxylic Acid Cycle

scholarly journals The Role of the Tricarboxylic Acid Cycle in Amino Acid Synthesis in Escherichia Coli

1953 ◽  
Vol 39 (10) ◽  
pp. 1013-1019 ◽  
Author(s):  
R. B. Roberts ◽  
D. B. Cowie ◽  
R. Britten ◽  
E. Bolton ◽  
P. H. Abelson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Tricarboxylic Acid Cycle ◽  
Acid Synthesis ◽  
Tricarboxylic Acid ◽  
Amino Acid Synthesis ◽  
Acid Cycle

scholarly journals Evidence for Autotrophic CO2 Fixation via the Reductive Tricarboxylic Acid Cycle by Members of the ε Subdivision of Proteobacteria

2005 ◽  
Vol 187 (9) ◽  
pp. 3020-3027 ◽  
Author(s):  
Michael Hügler ◽  
Carl O. Wirsen ◽  
Georg Fuchs ◽  
Craig D. Taylor ◽  
Stefan M. Sievert
Keyword(s):  
Carbon Fixation ◽  
Tricarboxylic Acid Cycle ◽  
Calvin Cycle ◽  
Tricarboxylic Acid ◽  
Rrna Gene ◽  
Atp Citrate Lyase ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Citrate Lyase ◽  
Reductive Tricarboxylic Acid Cycle

ABSTRACT Based on 16S rRNA gene surveys, bacteria of the ε subdivision of proteobacteria have been identified to be important members of microbial communities in a variety of environments, and quite a few have been demonstrated to grow autotrophically. However, no information exists on what pathway of autotrophic carbon fixation these bacteria might use. In this study, Thiomicrospira denitrificans and Candidatus Arcobacter sulfidicus, two chemolithoautotrophic sulfur oxidizers of the ε subdivision of proteobacteria, were examined for activities of the key enzymes of the known autotrophic CO2 fixation pathways. Both organisms contained activities of the key enzymes of the reductive tricarboxylic acid cycle, ATP citrate lyase, 2-oxoglutarate:ferredoxin oxidoreductase, and pyruvate:ferredoxin oxidoreductase. Furthermore, no activities of key enzymes of other CO2 fixation pathways, such as the Calvin cycle, the reductive acetyl coenzyme A pathway, and the 3-hydroxypropionate cycle, could be detected. In addition to the key enzymes, the activities of the other enzymes involved in the reductive tricarboxylic acid cycle could be measured. Sections of the genes encoding the α- and β-subunits of ATP citrate lyase could be amplified from both organisms. These findings represent the first direct evidence for the operation of the reductive tricarboxylic acid cycle for autotrophic CO2 fixation in ε-proteobacteria. Since ε-proteobacteria closely related to these two organisms are important in many habitats, such as hydrothermal vents, oxic-sulfidic interfaces, or oilfields, these results suggest that autotrophic CO2 fixation via the reductive tricarboxylic acid cycle might be more important than previously considered.

scholarly journals Transamination of glutamate to tricarboxylic acid-cycle intermediates in cultured neurons correlates with the ability of oxo acids to support neuronal survival in vitro

1986 ◽  
Vol 234 (3) ◽  
pp. 605-610 ◽  
Author(s):  
L Facci ◽  
S D Skaper ◽  
S Varon
Keyword(s):  
Amino Acid ◽  
Neuronal Survival ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Neuronal Cultures ◽  
Acid Cycle ◽  
Ciliary Ganglion Neurons ◽  
Amino Acid Precursors ◽  
Ganglion Neurons

Cultures of central-nervous-system neurons at low densities require for their survival exogenous pyruvate, alpha-oxoglutarate or oxaloacetate, even in the presence of high glucose concentrations. Most other alpha-oxo acids support cell survival only in the presence of alpha-amino acids which transaminate to alpha-oxoglutarate, oxaloacetate or pyruvate. The alpha-oxo acids therefore operate as acceptors of amino groups from appropriate donors to generate tricarboxylic acid-cycle-relevant substrates, and these alpha-oxo acids provide for neuronal support only insofar as they make it possible for exogenously supplied alpha-amino acid precursors to generate intracellularly one of the three critical metabolites. To examine more closely the relationship between transamination activity and neuronal survival, we measured 14CO2 production from [14C]glutamate in the presence of appropriate alpha-oxo acid partners by using 8-day-embryonic chick forebrain, dorsal-root-ganglion and ciliary-ganglion neurons. Neuronal survival was measured concurrently in monolayer neuronal cultures maintained with the corresponding amino acid/oxo acid pairs. Forebrain and ganglionic cell suspensions both produced 14CO2 from [14C]glutamate, which accurately correlated with 24 h neuronal survival. Concentrations of glutamate or alpha-oxo acid which provide for maximal neuronal survival also produced maximal amounts of 14CO2. The same ability to generate CO2 from glutamate (in the presence of the appropriate alpha-oxo acids) can ensure neuronal survival in 24 h cultures and therefore must meet energy or other metabolic needs of those neurons which glucose itself is unable to satisfy.

scholarly journals Carbon flux through photosynthesis and central carbon metabolism show distinct patterns between algae, C3 and C4 plants

Nature Plants ◽  
2021 ◽  
Author(s):  
Haim Treves ◽  
Anika Küken ◽  
Stéphanie Arrivault ◽  
Hirofumi Ishihara ◽  
Ines Hoppe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Higher Plants ◽  
Tricarboxylic Acid Cycle ◽  
Empirical Studies ◽  
Crop Improvement ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Central Carbon Metabolism ◽  
Amino Acid Synthesis

AbstractPhotosynthesis-related pathways are regarded as a promising avenue for crop improvement. Whilst empirical studies have shown that photosynthetic efficiency is higher in microalgae than in C3 or C4 crops, the underlying reasons remain unclear. Using a tailor-made microfluidics labelling system to supply 13CO2 at steady state, we investigated in vivo labelling kinetics in intermediates of the Calvin Benson cycle and sugar, starch, organic acid and amino acid synthesis pathways, and in protein and lipids, in Chlamydomonas reinhardtii, Chlorella sorokiniana and Chlorella ohadii, which is the fastest growing green alga on record. We estimated flux patterns in these algae and compared them with published and new data from C3 and C4 plants. Our analyses identify distinct flux patterns supporting faster growth in photosynthetic cells, with some of the algae exhibiting faster ribulose 1,5-bisphosphate regeneration and increased fluxes through the lower glycolysis and anaplerotic pathways towards the tricarboxylic acid cycle, amino acid synthesis and lipid synthesis than in higher plants.

scholarly journals Amino acid biosynthesis in mixed rumen cultures

1975 ◽  
Vol 150 (3) ◽  
pp. 357-372 ◽  
Author(s):  
F D Sauer ◽  
J D Erfle ◽  
S Mahadevan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Phosphoglyceric Acid ◽  
Amino Acid Precursors ◽  
Micro Organisms ◽  
Pyruvic Acids ◽  
Reductive Carboxylation

Mixed rumen micro-organisms, maintained in continuous culture readily incorporated labelled HCO3- and acetate into amino acids. Labelled propionate, in contrast, was utilized only for isoleucine biosynthesis, but failed to label other amino acids to any significant extent. Evidence was obtained showing that in these mixed, i.e. symbiotic, cultures foward tricarboxylic acid-cycle reactions only proceed to 2-oxoglutarate. 14C distribution in amino acids clearly shows that 2-oxoglutarate is not oxidized further by tricarboxylic acid-cycle enzymes. Instead, acetate is carboxylated to pyruvate which is then carboxylated to oxaloacetate. Oxaloacetate equilibrates with fumarate and thereby carbon atoms 1 and 4 as well as carbon atoms 2 and 3 are randomized. Evidence was also obtained for the carboxylation of propionate to 2-oxobutyrate, isovalerate to 4-methyl-2-oxopentanoate, phenylacetate and hydroxyphentlacetate to the corresponding phenyl- and hydroxyphenyl-pyruvic acids and succinate to 2-oxoglutarate. Of the amino acid precursors investigated, only 3-hydroxypyruvate, the precursor of serine, appeared to be synthesized via an oxidative step, i.e. 3-phosphoglyceric acid to 3-phosphohydroxypyruvic acid. Most 2-oxo precursors of amino acids in these organisms appear to be formed via reductive carboxylation of the precursor acid.

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