scholarly journals The Bifunctional Pyruvate Decarboxylase/Pyruvate Ferredoxin Oxidoreductase fromThermococcus guaymasensis

Archaea ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Mohammad S. Eram ◽  
Erica Oduaran ◽  
Kesen Ma
Keyword(s):  
Pyruvate Decarboxylase ◽  
Oxidative Decarboxylation ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Ferredoxin Oxidoreductase ◽  
Ph Values ◽  
Keto Acids ◽  
Genes Encoding ◽  
Oxygen Sensitive ◽  
Pyruvate Ferredoxin Oxidoreductase

The hyperthermophilic archaeonThermococcus guaymasensisproduces ethanol as a metabolic end product, and an alcohol dehydrogenase (ADH) catalyzing the reduction of acetaldehyde to ethanol has been purified and characterized. However, the enzyme catalyzing the formation of acetaldehyde has not been identified. In this study an enzyme catalyzing the production of acetaldehyde from pyruvate was purified and characterized fromT. guaymasensisunder strictly anaerobic conditions. The enzyme had both pyruvate decarboxylase (PDC) and pyruvate ferredoxin oxidoreductase (POR) activities. It was oxygen sensitive, and the optimal temperatures were 85°C and >95°C for the PDC and POR activities, respectively. The purified enzyme had activities of3.8±0.22 U mg−1and20.2±1.8 U mg−1, with optimal pH-values of 9.5 and 8.4 for each activity, respectively. Coenzyme A was essential for both activities, although it did not serve as a substrate for the former. Enzyme kinetic parameters were determined separately for each activity. The purified enzyme was a heterotetramer. The sequences of the genes encoding the subunits of the bifunctional PDC/POR were determined. It is predicted that all hyperthermophilicβ-keto acids ferredoxin oxidoreductases are bifunctional, catalyzing the activities of nonoxidative and oxidative decarboxylation of the correspondingβ-keto acids.

scholarly journals Metagenome Sequences of a Wastewater Treatment Plant Digester Sludge-Derived Enrichment Culture

2020 ◽  
Vol 9 (32) ◽  
Author(s):  
Heiko Nacke ◽  
Laura L. Kirck ◽  
Sophia Schwarz ◽  
Dominik Schneider ◽  
Anja Poehlein ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Microbial Community ◽  
Wastewater Treatment Plant ◽  
Enrichment Culture ◽  
Treatment Plant ◽  
Methanogenic Archaea ◽  
Metagenomic Analysis ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Genes Encoding

ABSTRACT We sequenced the metagenome of a microbial community enriched under strictly anaerobic conditions from wastewater treatment plant-derived digester sludge. The metagenomic analysis of the enrichment revealed that Acetobacterium and methanogenic archaea belonged to the dominant prokaryotes, and genes encoding components of the Wood-Ljungdahl pathway were identified.

scholarly journals Biochemical and Physiological Characterization of the Pyruvate Formate-Lyase Pfl1 of Chlamydomonas reinhardtii, a Typically Bacterial Enzyme in a Eukaryotic Alga

2008 ◽  
Vol 7 (3) ◽  
pp. 518-526 ◽  
Author(s):  
Anja Hemschemeier ◽  
Jessica Jacobs ◽  
Thomas Happe
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Anaerobic Metabolism ◽  
Pyruvate Decarboxylase ◽  
Pyruvate Formate Lyase ◽  
Physiological Characterization ◽  
Bacterial Enzyme ◽  
Genes Encoding ◽  
Oxygen Sensitive ◽  
Biochemical Analyses

ABSTRACT The unicellular green alga Chlamydomonas reinhardtii has a special type of anaerobic metabolism that is quite unusual for eukaryotes. It has two oxygen-sensitive [Fe-Fe] hydrogenases (EC 1.12.7.2) that are coupled to photosynthesis and, in addition, a formate- and ethanol-producing fermentative metabolism, which was proposed to be initiated by pyruvate formate-lyase (Pfl; EC 2.3.1.54). Pfl enzymes are commonly found in prokaryotes but only rarely in eukaryotes. Both the hydrogen- and the formate/ethanol-producing pathways are involved in a sustained anaerobic metabolism of the alga, which can be induced by sulfur depletion in illuminated cultures. Before now, the presence of a Pfl protein in C. reinhardtii was predicted from formate secretion and the homology of the deduced protein of the PFL1 gene model to known Pfl enzymes. In this study, we proved the formate-producing activity of the putative Pfl1 enzyme by heterologous expression of the C. reinhardtii PFL1 cDNA in Escherichia coli and subsequent in vitro activity tests of the purified protein. Furthermore, a Pfl-deficient E. coli strain secretes formate when expressing the PFL1 cDNA of C. reinhardtii. We also examined the Pfl1 fermentation pathway of C. reinhardtii under the physiological condition of sulfur depletion. Genetic and biochemical analyses show that sulfur-depleted algae express genes encoding enzymes acting downstream of Pfl1 and also potentially ethanol-producing enzymes, such as pyruvate decarboxylase (EC 4.1.1.1) or pyruvate ferredoxin oxidoreductase (EC 1.2.7.1). The latter enzymes might substitute for Pfl1 activity when Pfl1 is specifically inhibited by hypophosphite.

scholarly journals Escherichia Coli FeoC Binds a Redox-Active, Rapidly Oxygen-Sensitive [4Fe-4S] Cluster

2019 ◽  
Author(s):  
Aaron T. Smith ◽  
Richard O. Linkous ◽  
Nathan J. Max ◽  
Alexandrea E. Sestok ◽  
Veronika A. Szalai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Conformational Changes ◽  
Ferrous Iron ◽  
Iron Acquisition ◽  
Transcriptional Regulator ◽  
Cluster Decay ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Redox Active ◽  
Oxygen Sensitive

The acquisition of iron is essential to establishing virulence among most pathogens. Under acidic and/or anaerobic conditions, most bacteria utilize the widely-distributed ferrous iron (Fe<sup>2+</sup>) uptake (Feo) system to import metabolically-required iron. The Feo system is inadequately understood at the atomic, molecular, and mechanistic levels, but we do know it is comprised of a main membrane component (FeoB) essential for iron translocation, as well as two small, cytosolic proteins (FeoA and FeoC) hypothesized to function as accessories to this process. FeoC has many hypothetical functions, including that of an iron-responsive transcriptional regulator. Here, we demonstrate for the first time that <i>Escherichia coli </i>FeoC (<i>Ec</i>FeoC) binds an [Fe-S] cluster. Using electronic absorption, X-ray absorption, and electron paramagnetic resonance spectroscopies, we extensively characterize the nature of this cluster. Under strictly anaerobic conditions after chemical reconstitution, we demonstrate that <i>Ec</i>FeoC binds a redox-active [4Fe-4S]<sup>2+/+</sup>cluster that is rapidly oxygen-sensitive (<i>t<sub>½</sub></i>≈ 20 s), similar to the [Fe-S] cluster in the fumarate and nitrate reductase (FNR) transcriptional regulator. In a manner similar to FNR, we further probed the nature of the oxygen-induced cluster decay products and report conversion of a [4Fe-4S]<sup>2+</sup>cluster to a [2Fe-2S]<sup>2+</sup>cluster. In contrast to FNR, we show that [4Fe-4S]<sup>2+</sup>cluster binding to <i>Ec</i>FeoC is associated with modest conformational changes of the polypeptide, but not protein dimerization. Finally, we posit a working hypothesis in which the cluster-binding FeoCs may function as oxygen-sensitive iron sensors that fine-tune pathogenic ferrous iron acquisition.

Involvement of oxygen-sensitive pyruvate formate-lyase in mixed-acid fermentation by Streptococcus mutans under strictly anaerobic conditions

1982 ◽  
Vol 152 (1) ◽  
pp. 175-182
Author(s):  
K Abbe ◽  
S Takahashi ◽  
T Yamada
Keyword(s):  
Streptococcus Mutans ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Acid Fermentation ◽  
Pyruvate Formate Lyase ◽  
Fermentation Products ◽  
Mixed Acid ◽  
Volatile Products ◽  
Oxygen Sensitive ◽  
Fructose 1,6 Bisphosphate

Streptococcus mutans JC2 produced formate, acetate, ethanol, and lactate when suspensions were incubated with an excess of galactose or mannitol under strictly anaerobic conditions. The galactose- or mannitol-grown cell suspensions produced more formate, acetate, and ethanol than the glucose-grown cells even when incubated with glucose. The levels of lactate dehydrogenase and fructose 1,6-bisphosphate were not significantly different in these cells, but the level of pyruvate formate-lyase was higher in the galactose- or mannitol-grown cells, and that of triose phosphate was lower in the galactose-grown cells. This suggests that the regulation of pyruvate formate-lyase may play a major role in the change of the fermentation patterns. The cells of S. mutans grown on glucose produced a significant amount of volatile products even in the presence of excess glucose under strictly anaerobic conditions. However, when the anaerobically grown cells were exposed to air, only lactate was produced from glucose. When cells were anaerobically grown on mannitol and then exposed to air for 2 min, only trace amounts of fermentation products were formed from mannitol under anaerobic conditions. It was found that the pyruvate formate-lyase in the cells was inactivated by exposure of the cells to air.

scholarly journals Escherichia Coli FeoC Binds a Redox-Active, Rapidly Oxygen-Sensitive [4Fe-4S] Cluster

2019 ◽  
Author(s):  
Aaron T. Smith ◽  
Richard O. Linkous ◽  
Nathan J. Max ◽  
Alexandrea E. Sestok ◽  
Veronika A. Szalai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Conformational Changes ◽  
Ferrous Iron ◽  
Iron Acquisition ◽  
Transcriptional Regulator ◽  
Cluster Decay ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Redox Active ◽  
Oxygen Sensitive

The acquisition of iron is essential to establishing virulence among most pathogens. Under acidic and/or anaerobic conditions, most bacteria utilize the widely-distributed ferrous iron (Fe<sup>2+</sup>) uptake (Feo) system to import metabolically-required iron. The Feo system is inadequately understood at the atomic, molecular, and mechanistic levels, but we do know it is comprised of a main membrane component (FeoB) essential for iron translocation, as well as two small, cytosolic proteins (FeoA and FeoC) hypothesized to function as accessories to this process. FeoC has many hypothetical functions, including that of an iron-responsive transcriptional regulator. Here, we demonstrate for the first time that <i>Escherichia coli </i>FeoC (<i>Ec</i>FeoC) binds an [Fe-S] cluster. Using electronic absorption, X-ray absorption, and electron paramagnetic resonance spectroscopies, we extensively characterize the nature of this cluster. Under strictly anaerobic conditions after chemical reconstitution, we demonstrate that <i>Ec</i>FeoC binds a redox-active [4Fe-4S]<sup>2+/+</sup>cluster that is rapidly oxygen-sensitive (<i>t<sub>½</sub></i>≈ 20 s), similar to the [Fe-S] cluster in the fumarate and nitrate reductase (FNR) transcriptional regulator. In a manner similar to FNR, we further probed the nature of the oxygen-induced cluster decay products and report conversion of a [4Fe-4S]<sup>2+</sup>cluster to a [2Fe-2S]<sup>2+</sup>cluster. In contrast to FNR, we show that [4Fe-4S]<sup>2+</sup>cluster binding to <i>Ec</i>FeoC is associated with modest conformational changes of the polypeptide, but not protein dimerization. Finally, we posit a working hypothesis in which the cluster-binding FeoCs may function as oxygen-sensitive iron sensors that fine-tune pathogenic ferrous iron acquisition.

scholarly journals Pyruvate-Ferredoxin Oxidoreductase

1971 ◽  
Vol 246 (10) ◽  
pp. 3120-3125
Author(s):  
Kosaku Uyeda ◽  
Jesse C. Rabinowitz
Keyword(s):  
Ferredoxin Oxidoreductase ◽  
Pyruvate Ferredoxin Oxidoreductase

scholarly journals Engraftment of strictly anaerobic oxygen-sensitive bacteria in irritable bowel syndrome patients following fecal microbiota transplantation does not improve symptoms

Gut Microbes ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 1-16
Author(s):  
Patrick Denis Browne ◽  
Frederik Cold ◽  
Andreas Munk Petersen ◽  
Sofie Ingdam Halkjær ◽  
Alice Højer Christensen ◽  
...  
Keyword(s):  
Irritable Bowel Syndrome ◽  
Fecal Microbiota Transplantation ◽  
Fecal Microbiota ◽  
Strictly Anaerobic ◽  
Oxygen Sensitive ◽  
Irritable Bowel
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