scholarly journals Changes in ATP Sulfurylase activity in response to altered cyanobacteria growth conditions

2020 ◽  
Author(s):  
Lucia Gastoldi ◽  
Lewis M. Ward ◽  
Mayuko Nakagawa ◽  
Mario Giordano ◽  
Shawn E. McGlynn
Keyword(s):  
Growth Rate ◽  
Cell Growth ◽  
Redox Regulation ◽  
Specific Activity ◽  
Growth Conditions ◽  
Cell Physiology ◽  
Atp Sulfurylase ◽  
Environmental Media ◽  
Rate Limiting

Here we investigated variations in cell growth and ATP sulfurylase activity when two cyanobacterial strains – Synechocystis sp. PCC6803 and Synechococcus sp. WH7803 – were grown comparatively between conventional media and media with low ammonium, low sulfate and a controlled high CO2/low O2 atmosphere, which might resemble some Precambrian environments. In both organisms, a transition and adaptation to the reconstructed environmental media resulted in a decrease in ATPS specific activity. This decrease in activity appears to be decoupled from growth rate, suggesting the enzyme is not rate-limiting in S assimilation and raising questions about the role of ATPS redox regulation in cell physiology and thorughout history.

scholarly journals Reexamination of the Role of the Amino Terminus of SecA in Promoting Its Dimerization and Functional State

2008 ◽  
Vol 190 (21) ◽  
pp. 7302-7307 ◽  
Author(s):  
Sanchaita Das ◽  
Elizabeth Stivison ◽  
Ewa Folta-Stogniew ◽  
Donald Oliver
Keyword(s):  
Cell Growth ◽  
Functional State ◽  
Protein Translocation ◽  
Specific Activity ◽  
Cell Fractionation ◽  
Mutant Proteins ◽  
Amino Terminal ◽  
Carboxyl Terminal

ABSTRACT The SecA nanomotor promotes protein translocation in eubacteria by binding both protein cargo and the protein-conducting channel and by undergoing ATP-driven conformation cycles that drive this process. There are conflicting reports about whether SecA functions as a monomer or dimer during this dynamic process. Here we reexamined the roles of the amino and carboxyl termini of SecA in promoting its dimerization and functional state by examining three secA mutants and the corresponding proteins: SecAΔ8 lacking residues 2 to 8, SecAΔ11 lacking residues 2 to 11, and SecAΔ11/N95 lacking both residues 2 to 11 and the carboxyl-terminal 70 residues. We demonstrated that whether SecAΔ11 or SecAΔ11/N95 was functional for promoting cell growth depended solely on the vivo level of the protein, which appeared to govern residual dimerization. All three SecA mutant proteins were defective for promoting cell growth unless they were highly overproduced. Cell fractionation revealed that SecAΔ11 and SecAΔ11/N95 were proficient in membrane association, although the formation of integral membrane SecA was reduced. The presence of a modestly higher level of SecAΔ11/N95 in the membrane and the ability of this protein to form dimers, as detected by chemical cross-linking, were consistent with the higher level of secA expression and better growth of the SecAΔ11/N95 mutant than of the SecAΔ11 mutant. Biochemical studies showed that SecAΔ11 and SecAΔ11/N95 had identical dimerization defects, while SecAΔ8 was intermediate between these proteins and wild-type SecA in terms of dimer formation. Furthermore, both SecAΔ11 and SecAΔ11/N95 were equally defective in translocation ATPase specific activity. Our studies showed that the nonessential carboxyl-terminal 70 residues of SecA play no role in its dimerization, while increasing the truncation of the amino-terminal region of SecA from 8 to 11 residues results in increased defects in SecA dimerization and poor in vivo function unless the protein is highly overexpressed. They also clarified a number of conflicting previous reports and support the essential nature of the SecA dimer.

Role of Cl/Si Ratio in the Low-Temperature Chloro-Carbon Epitaxial Growth of SiC

2013 ◽  
Vol 740-742 ◽  
pp. 205-208
Author(s):  
Galyna Melnychuk ◽  
Siva Prasad Kotamraju ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
The Other ◽  
Additional Increase ◽  
Other Hand

In order to understand the influence of the Cl/Si ratio on the morphology of the low-temperature chloro-carbon epitaxial growth, HCl was added during the SiCl4/CH3Cl growth at 1300°C. Use of higher Cl/Si ratio allowed only modest improvements of the growth rate without morphology degradation, which did not go far beyond what has been achieved previously by optimizing the value of the input C/Si ratio. On the other hand, when the epitaxial growth process operated at too low or too high values of the input C/Si ratio, i.e., outside of the window of good epilayer morphology, any additional increase of the Cl/Si ratio caused improvement of the epilayer morphology. It was established that this improvement was due to a change of the effective C/Si ratio towards its intermediate values, which corresponded to more favorable growth conditions.

scholarly journals Cloning and Expression Analysis of One Gamma-Glutamylcysteine Synthetase Gene (Hbγ-ECS1) in Latex Production inHevea brasiliensis

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Wei Fang ◽  
Luo Shi Qiao ◽  
Wu Ming ◽  
Qiu Jian ◽  
Yang Wen Feng ◽  
...  
Keyword(s):  
Specific Activity ◽  
Rubber Tree ◽  
Natural Rubber Latex ◽  
Cloning And Expression ◽  
E Coli ◽  
Glutamylcysteine Synthetase ◽  
Commercial Source ◽  
Rate Limiting

Rubber tree is a major commercial source of natural rubber. Latex coagulation is delayed by thiols, which belong to the important type of antioxidants in laticifer submembrane, and is composed of glutathione (GSH), cysteine, and methionine. The rate-limiting enzyme,γ-ECS, plays an important role in regulating the biosynthesis of glutathione under any environment conditions. To understand the relation betweenγ-ECS and thiols and to correlate latex flow with one-time tapping and continuous tapping, we cloned and derived the full length of oneγ-ECS from rubber tree latex (Hbγ-ECS1). According to qPCR analysis, the expression levels ofHbγ-ECS1were induced by tapping and Ethrel stimulation, and the expression was related to thiols content in the latex. Continuous tapping induced injury, and the expression ofHbγECS1increased with routine tapping and Ethrel-stimulation tapping (more intensive tapping). According to expression in long-term flowing latex, the gene was related to the duration of latex flow.HbγECS1was expressed inE. coliRosetta using pET-sumo as an expression vector and the recombinant enzyme was purified; then we achieved 0.827 U/mg specific activity and about 66 kDa molecular weight. The present study can help us understand the complex role ofHbγ-ECSin thiols biosynthesis, which is influenced by tapping.

The Role of Copper in the Growth of Methylosinus trichosporium IMV 3011 and Poly-β-Hydroxybutyrate Biosynthesis

2012 ◽  
Vol 268-270 ◽  
pp. 221-224 ◽  
Author(s):  
Jing Dong
Keyword(s):  
Growth Rate ◽  
Cell Growth ◽  
Copper Concentration ◽  
Methane Monooxygenase ◽  
Lag Time ◽  
Particulate Methane Monooxygenase ◽  
Methylosinus Trichosporium ◽  
Monooxygenase Activity ◽  
Copper Addition

Methanotrophs are aerobic microorganisms that utilize methane as substrates for growth and PHB Biosynthesis. Copper plays an important role in cell growth and PHB biosynthesis. The effect of initial copper concentration on cultivation of M. trichosporium IMV 3011 on methane was investigated. With the addition of 30μmol/L CuSO4•5H2O, PMMO activity improved to 4 times of that without copper addition. The highest density of cultivated cells is 0.48g dry wtL-1, which is 2 times of that without copper addition. The lag time shortened to 15.87h, and the growth rate increased to 0.082h-1.The PHB content increased to 8.3%. It is found that certain initial copper concentration is beneficial to expression of high particulate methane monooxygenase activity, which may contribute to the synthesis of PHB in the cell.

The role of NAD(P)H:quinone oxidoreductase (NQO1) in redox regulation of pancreatic cancer cell growth

2003 ◽  
Vol 124 (4) ◽  
pp. A291
Author(s):  
Joseph Cullen ◽  
Marilyn Hinkhouse ◽  
Andrew Gaut ◽  
Jingru Liu ◽  
Christine Weydert ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Growth ◽  
Cancer Cell ◽  
Redox Regulation ◽  
Pancreatic Cancer Cell ◽  
Cancer Cell Growth

Redox Regulation of Pancreatic Cancer Cell Growth: Role of Glutathione Peroxidase in the Suppression of the Malignant Phenotype

2004 ◽  
Vol 15 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Jingru Liu ◽  
Marilyn M. Hinkhouse ◽  
Wenqing Sun ◽  
Christine J. Weydert ◽  
Justine M. Ritchie ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Growth ◽  
Glutathione Peroxidase ◽  
Cancer Cell ◽  
Redox Regulation ◽  
Pancreatic Cancer Cell ◽  
Malignant Phenotype ◽  
Cancer Cell Growth

Role of the exosporial membrane in attachment and germination of C. sporogenes

1993 ◽  
Vol 51 ◽  
pp. 38-39
Author(s):  
B.J. Panessa-Warren ◽  
G.T. Tortora ◽  
J.B. Warren
Keyword(s):  
Enzymatic Degradation ◽  
Light Transmission ◽  
Extended Period ◽  
Growth Conditions ◽  
Clostridium Sporogenes ◽  
Radiation Chemical ◽  
Physical Trauma ◽  
Extended Contact ◽  
Cold Pressure

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.

Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman
Keyword(s):  
Cytochrome C ◽  
Hydroxyl Radical ◽  
Redox Regulation ◽  
Chemotherapeutic Agents ◽  
Tyrosyl Radical ◽  
Compound I ◽  
Definitive Evidence ◽  
Enhanced Production ◽  
Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

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