scholarly journals Kinetic Analysis of the Oxidative Conversion of the [4Fe-4S]2+ Cluster of FNR to a [2Fe-2S]2+ Cluster

2004 ◽  
Vol 186 (23) ◽  
pp. 8018-8025 ◽  
Author(s):  
Victoria R. Sutton ◽  
Erin L. Mettert ◽  
Helmut Beinert ◽  
Patricia J. Kiley
Keyword(s):  
Oxidative Conversion ◽  
Anaerobic Conditions ◽  
Protein Levels ◽  
Detectable Difference ◽  
Fnr Protein ◽  
Sense And Respond ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT The ability of FNR to sense and respond to cellular O2 levels depends on its [4Fe-4S]2+ cluster. In the presence of O2, the [4Fe-4S]2+ cluster is converted to a [2Fe-2S]2+ cluster, which inactivates FNR as a transcriptional regulator. In this study, we demonstrate that ∼2 Fe2+ ions are released from the reaction of O2 with the [4Fe-4S]2+ cluster. Fe2+ release was then used as an assay of reaction progress to investigate the rate of [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion in vitro. We also found that there was no detectable difference in the rate of O2-induced cluster conversion for FNR free in solution compared to its DNA-bound form. In addition, the rate of FNR inactivation was monitored in vivo by measuring the rate at which transcriptional regulation by FNR is lost upon the exposure of cells to O2; a comparison of the in vitro and in vivo rates of conversion suggests that O2-induced cluster conversion is sufficient to explain FNR inactivation in cells. FNR protein levels were also compared for cells grown under aerobic and anaerobic conditions.

scholarly journals In vivo cycling of the Escherichia coli transcription factor FNR between active and inactive states

Microbiology ◽  
2005 ◽  
Vol 151 (12) ◽  
pp. 4063-4070 ◽  
Author(s):  
David P. Dibden ◽  
Jeffrey Green
Keyword(s):  
Escherichia Coli ◽  
De Novo ◽  
Oxygen Availability ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Fnr Protein ◽  
Transcription Regulators ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

FNR proteins are transcription regulators that sense changes in oxygen availability via assembly–disassembly of [4Fe–4S] clusters. The Escherichia coli FNR protein is present in bacteria grown under aerobic and anaerobic conditions. Under aerobic conditions, FNR is isolated as an inactive monomeric apoprotein, whereas under anaerobic conditions, FNR is present as an active dimeric holoprotein containing one [4Fe–4S] cluster per subunit. It has been suggested that the active and inactive forms of FNR are interconverted in vivo, or that iron–sulphur clusters are mostly incorporated into newly synthesized FNR. Here, experiments using a thermo-inducible fnr expression plasmid showed that a model FNR-dependent promoter is activated under anaerobic conditions by FNR that was synthesized under aerobic conditions. Immunoblots suggested that FNR was more prone to degradation under aerobic compared with anaerobic conditions, and that the ClpXP protease contributes to this degradation. Nevertheless, FNR was sufficiently long lived (half-life under aerobic conditions, ∼45 min) to allow cycling between active and inactive forms. Measuring the abundance of the FNR-activated dms transcript when chloramphenicol-treated cultures were switched between aerobic and anaerobic conditions showed that it increased when cultures were switched to anaerobic conditions, and decreased when aerobic conditions were restored. In contrast, measurement of the abundance of the FNR-repressed ndh transcript under the same conditions showed that it decreased upon switching to anaerobic conditions, and then increased when aerobic conditions were restored. The abundance of the FNR- and oxygen-independent tatE transcript was unaffected by changes in oxygen availability. Thus, the simplest explanation for the observations reported here is that the FNR protein can be switched between inactive and active forms in vivo in the absence of de novo protein synthesis.

Metabolite utilization by isolated embryonic rat hearts in vitro

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 235-245
Author(s):  
Steven J. Cox ◽  
David L. Gunberg
Keyword(s):  
Metabolic Pathways ◽  
Maximum Rate ◽  
Contractile Activity ◽  
Cardiac Contraction ◽  
Anaerobic Conditions ◽  
Isolated Hearts ◽  
Rat Hearts ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Isolated hearts from 11-, 12- and 13-day rat embryos were incubated in a simple defined salt solution to which was added a variety of single substrates. Utilization of the added substrate was determined by comparing the contractile rates of the hearts in the presence and absence of the compound being tested. Of all the compounds tested only those involved in the Embden-Meyerhof glycolytic pathway were capable of maintaining cardiac contraction at a maximum rate in the 11-day heart. This was accomplished under both aerobic and anaerobic conditions. Although glycolysis remained important, the 12- and 13-day hearts exhibited a shift in dependence towards other metabolic pathways. This conclusion was based on the observations that anaerobic glycolysis could no longer maintain maximum heart rates and that a variety of non-glycolytic compounds could be utilized for contractile activity by the 12- and 13-day organs.

Further evidence for the existence of cyclic and non-cyclic photophosphorylation in vivo by means of desaspidin and DCMU

1967 ◽  
Vol 22 (5) ◽  
pp. 537-540 ◽  
Author(s):  
W. Urbach ◽  
W. Simonis
Keyword(s):  
Antimycin A ◽  
Anaerobic Conditions ◽  
Intact Cells ◽  
Cyclic Photophosphorylation ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

The effect of desaspidin and DCMU on photophosphorylation in intact cells under aerobic and anaerobic conditions has been studied. Desaspidin is mainly effective in N2 and inhibits under these conditions the DCMU-insensitive cyclic photophosphorylation in vivo like antimycin A. The inhibition of the phosphorylation in light by DCMU is stronger in N2 than in air which suggests a partial existence of oxydative phosphorylation during illumination.

Organic Acids and Anaerobic Microorganisms in the Contents of the Cholesteatoma SAC

1983 ◽  
Vol 92 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Yukiko Iino ◽  
Tomonori Takasaka ◽  
Etsuro Hoshino ◽  
Yutaka Kaneko ◽  
Sachiko Tomioka ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Acids ◽  
Volatile Fatty Acids ◽  
Chromatographic Technique ◽  
Anaerobic Conditions ◽  
Clostridium Species ◽  
Anaerobic Microorganisms ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Organic acids in the contents of the cholesteatoma sac from 28 cases were studied by gas chromatographic technique. Five volatile fatty acids (acetate, propionate, isobutyrate, butyrate and isovalerate) and lactate were detected in large amounts, which may lower the pH of the cholesteatoma content. These acids were considered to be derived from products of anaerobic microorganisms. Therefore, the contents from 12 cases were cultured anaerobically in a glove box. Obligate microorganisms were identified in 92% of the cases and Peptococcus, Bacteroides, and Clostridium species were frequently isolated. In vitro, such obligate anaerobes produced various organic acids from the cholesteatoma content. Facultatives such as Staphylococcus aureus and Proteus mirabilis produced acetate in the content under aerobic and anaerobic conditions, whereas no organic acid was produced by Pseudomonas aeruginosa. Organic acids in the cholesteatoma content could be fermentative products made by the microorganisms, anaerobes and facultatives, which use the content as a substrate for acid production.

scholarly journals Production of Metastases by a Primary Tumour Irradiated under Aerobic and Anaerobic Conditions in vivo

1972 ◽  
Vol 26 (5) ◽  
pp. 402-412 ◽  
Author(s):  
H A S van den Brenk ◽  
V Moore ◽  
C Sharpington ◽  
C Orton
Keyword(s):  
Primary Tumour ◽  
Anaerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

The energy metabolism of adult Haemonchus contortus, in vitro

Parasitology ◽  
1978 ◽  
Vol 77 (3) ◽  
pp. 255-271 ◽  
Author(s):  
P. F. V. Ward ◽  
N. S. Huskisson
Keyword(s):  
Energy Metabolism ◽  
Haemonchus Contortus ◽  
Aerobic Incubation ◽  
Anaerobic Conditions ◽  
Physically Active ◽  
Aerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

SummaryA comparison was made of the major excretory products when adult Haemonchus contortus worms were incubated with D-[U-14C]glucose under aerobic and anaerobic conditions. Catabolites measured were propan-1-ol, acetate, n-propionate and CO2 and the only major difference was that nearly twice as much CO2 both in terms of quantity and radioactivity was excreted under aerobic than anaerobic conditions. The worms were also much more physically active under aerobic conditions. When worms were incubated under aerobic conditions with increasing amounts of fluoroacetate their CO2 production was progressively reduced to the anaerobic level. Their movement and their ability to clump together was also progressively reduced. After aerobic incubation with fluoroacetate and D-[U-14C]g1ucose the quantity and radioactivity of citrate within worms increased greatly. When worms were similarly incubated anaerobically no increase in citrate occurred, no radioactivity was associated with the citrate and the worms appeared physically unaffected. When worms were incubated aerobically with fluoro[1-14C]acetate they produced radioactive fluorocitrate.

Zellvermehrung und energieabhängige Stoffwechselleistungen von Ehrlich-Ascites-Zellen unter aeroben und anaeroben Bedingungen / Cell Division and Energy Dependent Metabolic Power of Ehrlich-Ascites-Tumor Cells Under Aerobic and Anaerobic Conditions

1971 ◽  
Vol 26 (8) ◽  
pp. 780-787 ◽  
Author(s):  
H. P. Krause ◽  
H. Probst ◽  
Fr. Schneider
Keyword(s):  
Cell Division ◽  
Tumor Cells ◽  
Ehrlich Ascites Tumor ◽  
Ehrlich Ascites Tumor Cells ◽  
Ascites Tumor ◽  
Anaerobic Conditions ◽  
Ehrlich Ascites ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Interrelations between energy metabolism and cell division were studied with permanent in vitro cultured Ehrlich-ascites-tumor-cells during the second passage in vitro. The following parameters were estimated under aerobic and anaerobic conditions and in the presence of dinitrophenol:DNA- and RNA-synthesis measured by the incorporation of 14C-thymidine and 14C-uridine; rate of glycolysis measured by lactate production; permeation of 14C-2-aminoisobutyric acid; ATP level of the cells; cell division and number of dead cells.The following results were obtained: Cell division and thymidine incorporation are obligate oxygen dependent processes. It was not possible to decide, whether respiration alone can maintain cell propagation. Respiration alone and glycolysis alone cannot maintain a normal level of ATP. Only an intact respiration can maintain the penetration of 2-aminoiso-butyric acid. Glycolysis alone and respiration alone can supply the energy for the incorporation of uridine. The incorporation of uridine is also influenced by oxygen dependent reactions not related to energy production. The number of dead cells does not rise significantly under anaerobic conditions.

scholarly journals Comparative Pharmacodynamics of Three Newer Fluoroquinolones versus Six Strains of Staphylococci in an In Vitro Model under Aerobic and Anaerobic Conditions

2002 ◽  
Vol 46 (5) ◽  
pp. 1561-1563 ◽  
Author(s):  
David H. Wright ◽  
Brent W. Gunderson ◽  
Laurie B. Hovde ◽  
Gigi H. Ross ◽  
Khalid H. Ibrahim ◽  
...  
Keyword(s):  
In Vitro Model ◽  
Pharmacodynamic Model ◽  
Clinical Isolates ◽  
Anaerobic Conditions ◽  
Vitro Model ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT Six strains of staphylococci were exposed to levofloxacin, moxifloxacin, or trovafloxacin in an in vitro pharmacodynamic model under both aerobic and anaerobic conditions. Each agent demonstrated a rapid 3-log10 kill versus susceptible isolates regardless of condition. Against clinical isolates with reduced susceptibility, regrowth occurred by 24 h and was frequently associated with further increases in MICs.

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