The central carbohydrate metabolism of the hyperthermophilic crenarchaeote Thermoproteus tenax: pathways and insights into their regulation

ABSTRACT In order to unravel the role of regulation on transcript level in central carbohydrate metabolism (CCM) of Thermoproteus tenax, a focused DNA microarray was constructed by using 85 open reading frames involved in CCM. A transcriptional analysis comparing heterotrophic growth on glucose versus autotrophic growth on CO2-H2 was performed.

Download Full-text

Reconstruction of the Central Carbohydrate Metabolism of Thermoproteus tenax by Use of Genomic and Biochemical Data

Journal of Bacteriology ◽

10.1128/jb.186.7.2179-2194.2004 ◽

2004 ◽

Vol 186 (7) ◽

pp. 2179-2194 ◽

Cited By ~ 55

Author(s):

Bettina Siebers ◽

Britta Tjaden ◽

Klaus Michalke ◽

Christine Dörr ◽

Hatim Ahmed ◽

...

Keyword(s):

Carbohydrate Metabolism ◽

Citric Acid Cycle ◽

Growth Conditions ◽

Pentose Phosphate ◽

Trehalose Metabolism ◽

Thermoproteus Tenax ◽

Almost All ◽

Low Coverage ◽

Central Carbohydrate Metabolism ◽

Carbohydrate Catabolism

ABSTRACT The hyperthermophilic, facultatively heterotrophic crenarchaeum Thermoproteus tenax was analyzed using a low-coverage shotgun-sequencing approach. A total of 1.81 Mbp (representing 98.5% of the total genome), with an average gap size of 100 bp and 5.3-fold coverage, are reported, giving insights into the genome of T. tenax. Genome analysis and biochemical studies enabled us to reconstruct its central carbohydrate metabolism. T. tenax uses a variant of the reversible Embden-Meyerhof-Parnas (EMP) pathway and two different variants of the Entner-Doudoroff (ED) pathway (a nonphosphorylative variant and a semiphosphorylative variant) for carbohydrate catabolism. For the EMP pathway some new, unexpected enzymes were identified. The semiphosphorylative ED pathway, hitherto supposed to be active only in halophiles, is found in T. tenax. No evidence for a functional pentose phosphate pathway, which is essential for the generation of pentoses and NADPH for anabolic purposes in bacteria and eucarya, is found in T. tenax. Most genes involved in the reversible citric acid cycle were identified, suggesting the presence of a functional oxidative cycle under heterotrophic growth conditions and a reductive cycle for CO2 fixation under autotrophic growth conditions. Almost all genes necessary for glycogen and trehalose metabolism were identified in the T. tenax genome.

Download Full-text

Impaired chloroplast positioning affects photosynthetic capacity and regulation of the central carbohydrate metabolism during cold acclimation

10.1101/2020.05.06.080531 ◽

2020 ◽

Author(s):

Anastasia Kitashova ◽

Katja Schneider ◽

Lisa Fürtauer ◽

Laura Schröder ◽

Tim Scheibenbogen ◽

...

Keyword(s):

Carbohydrate Metabolism ◽

Cold Acclimation ◽

Metabolic Regulation ◽

Environmental Changes ◽

Higher Plants ◽

Biomass Accumulation ◽

Sucrose Phosphate Synthase ◽

Low Light ◽

Reduced Rate ◽

Central Carbohydrate Metabolism

AbstractPhotosynthesis and carbohydrate metabolism of higher plants need to be tightly regulated to prevent tissue damage during environmental changes. The intracellular position of chloroplasts changes due to a changing light regime. Chloroplast avoidance and accumulation response under high and low light, respectively, are well known phenomena, and deficiency of chloroplast movement has been shown to result in photodamage and reduced biomass accumulation. Yet, effects of chloroplast positioning on underlying metabolic regulation are less well understood. Here, we analysed photosynthesis together with metabolites and enzyme activities of the central carbohydrate metabolism during cold acclimation of the chloroplast unusual positioning 1 (chup1) mutant of Arabidopsis thaliana. We compared cold acclimation under ambient and low light and found that maximum quantum yield of PSII was significantly lower in chup1 than in Col-0 under both conditions. Our findings indicated that net CO2 assimilation in chup1 is rather limited by biochemistry than by photochemistry. Further, cold-induced dynamics of sucrose phosphate synthase differed significantly between both genotypes. Together with a reduced rate of sucrose cycling derived from kinetic model simulations our study provides evidence for a central role of chloroplast positioning for photosynthetic and metabolic acclimation to low temperature.

Download Full-text