Structure of thylakoids in cells of Rhodopseudomonas viridis as influenced by growth conditions

1985 ◽  
Vol 141 (4) ◽  
pp. 325-329 ◽  
Author(s):  
W. Welte ◽  
W. Kreutz
Keyword(s):  
Growth Conditions ◽  
Rhodopseudomonas Viridis ◽  
In Cells

scholarly journals Superoxide dismutase, catalase, and peroxidase in ammonium-grown and nitrogen-fixing Azospirillum brasilense

1984 ◽  
Vol 30 (10) ◽  
pp. 1222-1228 ◽  
Author(s):  
Richard W. Clara ◽  
Roger Knowles
Keyword(s):  
Superoxide Dismutase ◽  
Electron Acceptor ◽  
Azospirillum Brasilense ◽  
Polyacrylamide Gel Electrophoresis ◽  
Growth Conditions ◽  
Sod Activity ◽  
Batch Cultures ◽  
Physiological Conditions ◽  
Azospirillum Brasilense Sp7 ◽  
In Cells

Superoxide dismutase (SOD), catalase (CAT), and peroxidase (PER) activities were studied in ammonium-grown and N2-fixing batch cultures of Azospirillum brasilense Sp7. PER activity, as measured using o-dianisidine or 3,3′-diaminobenzidine as the H donor, was not significant in most growth conditions. SOD activity increased in response to higher O2 concentrations but was also present in cells grown anaerobically with nitrate [Formula: see text] or nitrous oxide (N2O) as electron acceptor. CAT activity increased at lower O2 concentrations and was highest in cells grown anaerobically with [Formula: see text] as electron acceptor. Polyacrylamide gel electrophoresis of cell-free extracts revealed only one band of SOD activity under each of the physiological conditions employed, compared with three for aerobically grown Escherichia coli K12. This band proved to be iron-containing SOD (FeSOD) on the basis of inhibitor sensitivity.

ABF1 is a phosphoprotein and plays a role in carbon source control of COX6 transcription in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (9) ◽  
pp. 4197-4208
Author(s):  
S Silve ◽  
P R Rhode ◽  
B Coll ◽  
J Campbell ◽  
R O Poyton
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Glucose Repression ◽  
Carbon Sources ◽  
Growth Conditions ◽  
Source Control ◽  
Specific Target Gene ◽  
Phosphorylation Pattern ◽  
Nonfermentable Carbon Source ◽  
In Cells

Previously, we have shown that the Saccharomyces cerevisiae DNA-binding protein ABF1 exists in at least two different electrophoretic forms (K. S. Sweder, P. R. Rhode, and J. L. Campbell, J. Biol. Chem. 263: 17270-17277, 1988). In this report, we show that these forms represent different states of phosphorylation of ABF1 and that at least four different phosphorylation states can be resolved electrophoretically. The ratios of these states to one another differ according to growth conditions and carbon source. Phosphorylation of ABF1 is therefore a regulated process. In nitrogen-starved cells or in cells grown on nonfermentable carbon sources (e.g., lactate), phosphorylated forms predominate, while in cells grown on fermentable carbon sources (e.g., glucose), dephosphorylated forms are enriched. The phosphorylation pattern is affected by mutations in the SNF1-SSN6 pathway, which is involved in glucose repression-depression. Whereas a functional SNF1 gene, which encodes a protein kinase, is not required for the phosphorylation of ABF1, a functional SSN6 gene is required for itsd ephosphorylation. The phosphorylation patterns that we have observed correlate with the regulation of a specific target gene, COX6, which encodes subunit VI of cytochrome c oxidase. Transcription of COX6 is repressed by growth in medium containing a fermentable carbon source and is derepressed by growth in medium containing a nonfermentable carbon source. COX6 repression-derepression is under the control of the SNF1-SSN6 pathway. This carbon source regulation is exerted through domain 1, a region of the upstream activation sequence UAS6 that binds ABF1 (J. D. Trawick, N. Kraut, F. Simon, and R. O. Poyton, Mol. Cell Biol. 12:2302-2314, 1992). We show that the greater the phosphorylation of ABF1, the greater the transcription of COX6. Furthermore, the ABF1-containing protein-DNA complexes formed at domain 1 differ according to the phosphorylation state of ABF1 and the carbon source on which the cells were grown. From these findings, we propose that the phosphorylation of ABF1 is involved in glucose repression-derepression of COX6 transcription.

scholarly journals Effect of Anaerobiosis on Expression of Virulence Factors in Vibrio cholerae

2004 ◽  
Vol 72 (7) ◽  
pp. 3961-3967 ◽  
Author(s):  
H. H. Krishnan ◽  
Amalendu Ghosh ◽  
Kalidas Paul ◽  
Rukhsana Chowdhury
Keyword(s):  
Vibrio Cholerae ◽  
Virulence Factors ◽  
Regulatory Gene ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Anaerobic Conditions ◽  
Regulatory Cascade ◽  
Significant Difference ◽  
In Cells

ABSTRACT In Vibrio cholerae, the transmembrane DNA binding proteins, ToxR and TcpP, activate expression of the regulatory gene toxT in response to specific environmental signals. The resulting enhanced level of ToxT leads to a coordinated increase in the production of a subset of virulence factors, including cholera toxin (CT) and toxin-coregulated pilus (TCP). The effect of anaerobiosis on expression of the V. cholerae virulence regulatory cascade was examined. The expression of the major regulatory genes, tcpP, toxR, and toxT, in anaerobically grown V. cholerae was comparable to that in cells grown under aerobic conditions, and no significant difference in the ToxT-dependent expression of tcpA was detected when aerobic and anaerobic cultures were compared. However, in spite of the presence of functional ToxT, ctxAB expression was drastically reduced, and practically no CT was detected in cells grown under anaerobic conditions. In a V. cholerae hns mutant, however, high levels of ctxAB expression occurred even under anaerobic conditions. Also, deletion of the H-NS binding site from the ctxAB promoter eliminated anaerobic repression of ctxAB expression. These results suggest that H-NS directly represses ctxAB expression under anaerobic growth conditions. It has been reported that in the first stage of infection of infant mice by V. cholerae, tcpA is expressed but ctxAB expression is shut off (S. H. Lee, D. L. Hava, M. K. Waldor, and A. Camilli, Cell 99: 625-634, 1999). This pattern is similar to the pattern in anaerobic cultures of V. cholerae. Under all other in vitro conditions, ctxAB and tcpA are known to be coordinately expressed.

Differentiation of the membrane system in cells of Rhodopseudomonas capsulata after transition from chemotrophic to phototrophic growth conditions

1982 ◽  
Vol 131 (4) ◽  
pp. 313-322 ◽  
Author(s):  
Norbert Kaufmann ◽  
Horst-Helwig Reidl ◽  
Jochen R. Golecki ◽  
Augusto F. Garcia ◽  
Gerhart Drews
Keyword(s):  
Membrane System ◽  
Growth Conditions ◽  
Rhodopseudomonas Capsulata ◽  
Phototrophic Growth ◽  
In Cells

scholarly journals Alternative Oxidase Activity Reduces Stress in Vibrio fischeri Cells Exposed to Nitric Oxide

2018 ◽  
Vol 200 (15) ◽  
Author(s):  
Anne K. Dunn
Keyword(s):  
Nitric Oxide ◽  
Alternative Oxidase ◽  
Vibrio Fischeri ◽  
Membrane Integrity ◽  
Model Organism ◽  
Growth Conditions ◽  
Respiratory Pathway ◽  
Content Type ◽  
Atp Production ◽  
In Cells

ABSTRACT Alternative oxidase (Aox) is a non-energy-conserving respiratory oxidase found in certain eukaryotes and bacteria, whose role in physiology is not entirely clear. Using the genetically tractable bacterium Vibrio fischeri as a model organism, I have identified a role for Aox to reduce levels of stress in cells exposed to oxygen and nitric oxide (NO). In V. fischeri lacking the NO-detoxifying enzyme flavohemoglobin (Hmp), deletion of aox in cells grown in the presence of oxygen and NO results in alterations to the transcriptome that include increases in transcripts mapping to stress-related genes. Using fluorescence-based reporters, I identified corresponding increases in intracellular reactive oxygen species and decreases in membrane integrity in cells lacking aox. Under these growth conditions, activity of Aox is linked to a decrease in NADH levels, indicating coupling of Aox activity with NADH dehydrogenase activity. Taken together, these results suggest that Aox functions to indirectly limit production of ferrous iron and damaging hydroxyl radicals, effectively reducing cellular stress during NO exposure. IMPORTANCE Unlike typical respiratory oxidases, alternative oxidase (Aox) does not directly contribute to energy conservation, and its activity would presumably reduce the efficiency of respiration and associated ATP production. Aox has been identified in certain bacteria, a majority of which are marine associated. The presence of Aox in these bacteria poses the interesting question of how Aox function benefits bacterial growth and survival in the ocean. Using the genetically tractable marine bacterium Vibrio fischeri, I have identified a role for Aox in reduction of stress under conditions where electron flux through the aerobic respiratory pathway is inhibited. These results suggest that Aox activity could positively impact longer-term bacterial fitness and survival under stressful environmental conditions.

Impact of growth environment and physiological state on metal immobilization byPseudomonas aeruginosaPAO1

2010 ◽  
Vol 56 (7) ◽  
pp. 527-538 ◽  
Author(s):  
Ryan C. Hunter ◽  
Vernon R. Phoenix ◽  
Anuradha Saxena ◽  
Terry J. Beveridge
Keyword(s):  
Metal Binding ◽  
Physiological State ◽  
Growth Conditions ◽  
Spectrophotometric Analysis ◽  
Cell Physiology ◽  
Growth Environment ◽  
Bacterial Surface ◽  
Metal Interactions ◽  
Metal Immobilization ◽  
In Cells

Environmental growth conditions and cell physiology have the potential to influence bacterial surface–metal interactions in both planktonic and biofilm systems. Here, Pseudomonas aeruginosa was studied to determine the influence of these factors (pH, redox potential, and active respiration) on surface electrostatics and metal immobilization. Acid–base titrations revealed a decrease in ionizable ligands at pKa5 (putative carboxyls) in cells grown below pH 6.2 and in cells grown anaerobically relative to cells grown under oxic and circumneutral pH conditions. This observation correlates with Western immunoblotting assays that revealed a reduction in carboxylated B-band lipopolysaccharide in these cells. Furthermore, spectrophotometric analysis revealed a decrease in zinc, copper, and iron immobilization in these cells, suggesting that lipopolysaccharide modification in response to environmental stimuli influences metal binding. The effect of active versus inactive metabolism on metal adsorption was also examined using respiration inhibitors carbonyl cyanide m-chlorophenylhydrazone and sodium azide. Cells treated with these compounds bound more zinc, copper, and iron than untreated controls, suggesting proton extrusion through respiration competes with metal cations for reactive groups on the cell surface. Accumulation of gold did not show the same trend, and transmission electron microscopy studies confirmed it was not a surface-mediated process. These results suggest that variations in growth environment and cell physiology influence metal accumulation by bacterial cell surfaces and may help to explain discontinuous accumulation of metal observed throughout microbial communities.

scholarly journals Biosynthesis of soluble carnitine acetyltransferases from the yeast Candida tropicalis

1988 ◽  
Vol 253 (3) ◽  
pp. 845-849 ◽  
Author(s):  
B Kozulić ◽  
K Mosbach ◽  
F Meussdoerffer
Keyword(s):  
Continuous Culture ◽  
Candida Tropicalis ◽  
Growth Conditions ◽  
Proteolytic Processing ◽  
Carnitine Acetyltransferase ◽  
Acetyltransferase Activity ◽  
Tetrameric Form ◽  
In Cells

Soluble carnitine acetyltransferase from Candida tropicalis is synthesized as a 76 kDa precursor, which is monomeric and possesses no or very little carnitine acetyltransferase activity. Maturation of the enzyme begins with proteolytic processing of the 76 kDa precursor to 64 and 57 kDa subunits. The processed subunits subsequently associate into two kinds of active oligomers; the 57 kDa subunits are assembled into a tetramer and the 64 kDa subunits into an octamer. Formation of these oligomers depends apparently on growth conditions, since both oligomers were present in cells grown in continuous culture, but cells grown batchwise contained only the tetrameric form of carnitine acetyltransferase.

scholarly journals Thermoprotection of Bacillus subtilis by Exogenously Provided Glycine Betaine and Structurally Related Compatible Solutes: Involvement of Opu Transporters

2004 ◽  
Vol 186 (6) ◽  
pp. 1683-1693 ◽  
Author(s):  
Gudrun Holtmann ◽  
Erhard Bremer
Keyword(s):  
Bacillus Subtilis ◽  
Glycine Betaine ◽  
Compatible Solutes ◽  
Physiological Role ◽  
Growth Conditions ◽  
Transport Systems ◽  
Moderate Increase ◽  
Low Concentrations ◽  
In Cells

ABSTRACT Bacillus subtilis possesses five osmotically regulated transporters (Opu) for the uptake of various compatible solutes for osmoprotective purposes. We have now found that compatible solutes also function as thermoprotectants for B. subtilis. Low concentrations of glycine betaine enhanced the growth of the B. subtilis wild-type strain JH642 at its maximal growth temperature (52°C) but did not allow an extension of the upper growth limit. A similar enhancement in the growth of B. subtilis was also observed by the addition of several other compatible solutes that are structurally related to glycine betaine or by the addition of proline. Each of these compatible solutes was taken up under heat stress by the cell through the same Opu transporters that are used for their acquisition under osmostress conditions. Northern blot analysis revealed a moderate increase in transcription of the structural genes for each of the Opu transport systems in cells that were propagated at 52°C. In contrast, the uptake level of radiolabeled glycine betaine was very low under high-temperature growth conditions but nevertheless allowed the buildup of an intracellular glycine betaine pool comparable to that found in cells grown at 37°C in the absence of salt stress. Although exogenously added glutamate has only a limited osmoprotective potential for B. subtilis, it was found to be a very effective thermoprotectant. Collectively, our data demonstrate thermoprotection by a variety of compatible solutes in B. subtilis, thus ascribing a new physiological function for this class of compounds in this microorganism and broadening the physiological role of the known osmoprotectant uptake systems (Opu).

Changing patterns of 32P and 33P utilization in cells of Candida utilis during the cell cycle

1972 ◽  
Vol 18 (11) ◽  
pp. 1691-1693 ◽  
Author(s):  
P. S. S. Dawson ◽  
H. Glättli
Keyword(s):  
Cell Cycle ◽  
Doubling Time ◽  
Candida Utilis ◽  
Cold Water ◽  
Growth Conditions ◽  
Changing Patterns ◽  
Rna And Dna ◽  
Synchronized Cultures ◽  
In Cells

Incorporation of 33P and 32P into different fractions of continuous phased (synchronized) cultures of Candida utilis was studied. Two different growth conditions (on C-limited and N-limited media) were used at a doubling time of 6 h. Incorporation of 33P and 32P into four fractions (lipid, cold-water ex-tractable, RNA and DNA) showed a variable, nonuniform, behavior during the cell cycle. Different patterns of incorporation between cells on the two media were observed.

Precocious S-Phase Entry in Budding Yeast Prolongs Replicative State and Increases Dependence Upon Rad53 for Viability

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 123-136
Author(s):  
Julia M Sidorova ◽  
Linda L Breeden
Keyword(s):  
Kinase Activity ◽  
Growth Conditions ◽  
S Phase ◽  
Wild Type ◽  
Origin Firing ◽  
Phase Progression ◽  
Rad53 Kinase ◽  
Replication Intermediates ◽  
Phase Entry ◽  
In Cells

Abstract Precocious entry into S phase due to overproduction of G1 regulators can cause genomic instability. The mechanisms of this phenomenon are largely unknown. We explored the consequences of precocious S phase in yeast by overproducing a deregulated form of Swi4 (Swi4-t). Swi4 is a late G1-specific transcriptional activator that, in complex with Swi6, binds to SCB elements and activates late G1-specific genes, including G1 cyclins. We find that wild-type cells tolerate Swi4-t, whereas checkpoint-deficient rad53-11 cells lose viability within several divisions when Swi4-t is overproduced. Rad53 kinase activity is increased in cells overproducing Swi4-t, indicating activation of the checkpoint. We monitored the transition from G1 to S in cells with Swi4-t and found that there is precocious S-phase entry and that the length of S phase is extended. Moreover, there were more replication intermediates, and firing of at least a subset of origins may have been more extensive in the cells expressing Swi4-t. Our working hypothesis is that Rad53 modulates origin firing based upon growth conditions to optimize the rate of S-phase progression without adversely affecting fidelity. This regulation becomes essential when S phase is influenced by Swi4-t.

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