Dataset Information

Carbon fixation in the chemolithoautotrophic bacterium Aquifex aeolicus involves two low-potential ferredoxins as partners of the pentameric PFOR and OGOR enzymes

ABSTRACT: Aquifex aeolicus is a microaerophilic hydrogen- and sulfur -oxidizing bacterium that assimilates CO2 via the reverse tricarboxylic acid cycle (rTCA). Key enzymes of this pathway are pyruvate:ferredoxin oxidoreductase (PFOR) and 2-oxoglutarate:ferredoxin oxidoreductase (OGOR), which are responsible, respectively, for the reductive carboxylation of acetyl-CoA to pyruvate and of succinyl-CoA to 2-oxoglutarate, two energetically unfavorable reactions that require a strong reduction potential. We have confirmed, by biochemistry and proteomics, that A. aeolicus possesses a pentameric version of these enzyme complexes ((αβγδε)2) and that they are highly abundant in the cell. In addition, we have purified and characterized from the soluble fraction of A. aeolicus, two low redox potential and oxygen-stable [4Fe-4S] ferredoxins (Fd6 and Fd7, E0 = -440 and -460 mV respectively) and have shown that they can physically interact and exchange electrons with both PFOR and OGOR, suggesting that they could be the physiological electron donors of the system in vivo. Shotgun proteomics indicated that all the enzymes assumed to be involved in the rTCA cycle are produced in the A. aeolicus cells. A number of additional enzymes, previously suggested to be part of a putative partial Wood-Ljungdahl pathway used for the synthesis of serine and glycine from CO2 [1], were identified by mass spectrometry, but their abundance in the cell seem to be much lower than those of the rTCA cycle. Their possible involvement in the carbon assimilation is discussed. 1- Braakman, R.; Smith, E. Metabolic Evolution of a Deep-Branching Hyperthermophilic Chemoautotrophic Bacterium. PloS One 2014, 9, e87950, doi:10.1371/journal.pone.0087950.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Aquifex Aeolicus

SUBMITTER: Regine Lebrun

LAB HEAD: Lebrun Regine

PROVIDER: PXD040248 | Pride | 2023-05-10

REPOSITORIES: Pride

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Publications

Carbon Fixation in the Chemolithoautotrophic Bacterium Aquifex aeolicus Involves Two Low-Potential Ferredoxins as Partners of the PFOR and OGOR Enzymes.

Prioretti Laura L D'Ermo Giulia G Infossi Pascale P Kpebe Arlette A Lebrun Régine R Bauzan Marielle M Lojou Elisabeth E Guigliarelli Bruno B Giudici-Orticoni Marie-Thérèse MT Guiral Marianne M

Life (Basel, Switzerland) 20230223 3

Aquifex aeolicus is a microaerophilic hydrogen- and sulfur -oxidizing bacterium that assimilates CO2 via the reverse tricarboxylic acid cycle (rTCA). Key enzymes of this pathway are pyruvate:ferredoxin oxidoreductase (PFOR) and 2-oxoglutarate:ferredoxin oxidoreductase (OGOR), which are responsible, respectively, for the reductive carboxylation of acetyl-CoA to pyruvate and of succinyl-CoA to 2-oxoglutarate, two energetically unfavorable reactions that require a strong reduction ...[more]

PMID: 36983784

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Project description:Arabidopsis thaliana plants that have experienced an initial exposure to dehydration stress (“trained plants”) have an increased ability to maintain leaf relative water content (RWC) during subsequent stresses than plants experiencing the stress for the first time and transcription of selected dehydration response genes is altered during successive exposures to dehydration stress. This physiological and transcriptional behavior of trained plants is consistent with a “memory “of an earlier stress. It is unknown whether such memory is present in other Angiosperm lineages and whether it is an evolutionarily conserved response to stress (see E-GEOD-48235). Here, we analyzed the behavior and transcriptomes of maize (Zea mays) plants experiencing multiple dehydration stresses and compare them with responses of the evolutionarily distant A. thaliana. We found structurally related genes in maize that displayed the same memory-type responses as in A. thaliana, providing evidence of the conservation of function and transcriptional memory in the evolution of plants’ dehydration stress response systems. Similar to A. thaliana, trained Z. mays plants retained higher RWC during dehydration stress than untrained plants, due in part to maintaining reduced stomatal conductance, despite full recovery of RWC, after the first stress. Divergent transcriptional memory responses were also expressed, suggesting diversification of function among stress memory genes. Some dehydration stress memory genes were also shared with other stress and hormone responding pathways, indicating complex and dynamic interactions between different plant signaling networks. The results provide new insight into how plants respond to multiple dehydration stresses and provide a platform for studies of the functions of memory genes in adaptive responses to water deficit in monocot and eudicot plants . For each condition (water, S1, and S3) the transcriptome was sequenced for two replicates. The watered condition is considered the control.

Dataset Information

Carbon fixation in the chemolithoautotrophic bacterium Aquifex aeolicus involves two low-potential ferredoxins as partners of the pentameric PFOR and OGOR enzymes

Publications

Carbon Fixation in the Chemolithoautotrophic Bacterium <i>Aquifex aeolicus</i> Involves Two Low-Potential Ferredoxins as Partners of the PFOR and OGOR Enzymes.

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