Pressure-induced inactivation of E. coli β-galactosidase: influence of pH and temperatur

Degraeve, Pascal; Delorme, P.; Lemay, Pierre

doi:10.1016/0167-4838(95)00196-4

Cited by 27 publications

(10 citation statements)

References 25 publications

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“…Alternatively, the apparent decrease in ␤-galactosidase activity in cultures grown at pH 5.8 might reflect the requirement for translation or for extended transcripts, neither of which would be required for detection of short mRNA species via RT-PCR. Note that the activity of the ␤-galactosidase enzyme is not affected in the pH ranges tested in this study (19). In the cRT-PCR experiments, which require the smallest stretch of transcript for detection, we observed the highest steady-state levels of tbp-specific message, suggesting that growth at pH 5.8 might actually induce transcription from the tbp promoter but that there is concomitant degradation of long messages, resulting in decreased translatability.…”

Section: Vol 69 2001mentioning

confidence: 65%

Gonococcal Genes Encoding Transferrin-Binding Proteins A and B Are Arranged in a Bicistronic Operon but Are Subject to Differential Expression

2001

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Neisseria gonorrhoeae is capable of utilizing host iron-binding proteins, such as transferrin, lactoferrin, and hemoglobin, as the sole source of iron. The receptor involved in transferrin iron acquisition is composed of two distinct transferrin-binding proteins, TbpA and TbpB. The genes that encode these proteins are linked on the chromosome in the order tbpB-tbpA but are separated by an inverted repeat of unknown function. In this study, we sought to understand the transcriptional organization and regulation of the tbp genes, using a combination of lacZ transcriptional fusion analysis and reverse transcriptase PCR (RT-PCR). First, we demonstrated that tbpB and tbpA are cotranscribed and coregulated from the common upstream promoter that precedes tbpB. Using ␤-galactosidase activity as a surrogate for tbp-specific transcription, we found that tbpB-specific transcripts were more prevalent than tbpA-specific transcripts after 2 h of growth under iron stress conditions. We confirmed the results obtained by fusion analysis by using RT-PCR applied to native RNA isolated from wild-type gonococci. Three different varieties of RT-PCR were employed: relative, competitive, and real time quantitative. The results of all analyses indicated that tbpB-specific transcripts were approximately twofold more prevalent than tbpA-specific transcripts at steady state. In iron-stressed cultures, the ratio of tbpB-to tbpA-specific message was approximately 2; however, in iron-replete cultures, this ratio dropped to 1. Using these techniques, we also quantitated the effects of iron, external pH, and presence of ligand on tbp mRNA levels.Pathogenic bacteria must obtain essential nutrients in order to establish an infection; of these nutrients, iron plays a critical role (for a recent review, see reference 53).

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Section: Vol 69 2001mentioning

confidence: 65%

Gonococcal Genes Encoding Transferrin-Binding Proteins A and B Are Arranged in a Bicistronic Operon but Are Subject to Differential Expression

2001

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“…Thus it was concluded that at all but the lowest pH values, the β-galactosidase activities arising from the yfiD ::lac reporter plasmid (pGS1000) reflected the production of YfiD protein. The possibility that the difference between the two measures of YfiD production at the lowest pH values may arise from a reduction in reporter plasmid copy number under these conditions cannot be excluded, but because it is known that β-galactosidase is sensitive to pH values below 6n0 (Degraeve et al, 1996) Expression of yfiD as monitored by the yfiD ::lac reporter fusion pGS1000 in the presence or absence of the transcription factors FNR, ArcA and PdhR, and the effect of acidity on the activity of these regulators. As a control, the effects of the imposed genetic and environmental conditions on the expression of the FNR-regulated model promoter FF-41.5 were also assessed.…”

Section: Expression Of β-Galactosidase From a Yfid::lac Reporter Is Amentioning

confidence: 99%

Expression of the Escherichia coli yfiD gene responds to intracellular pH and reduces the accumulation of acidic metabolic end products

et al. 2002

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The YfiD protein of Escherichia coli has been reported to be an acid-inducible protein.Here it is shown that expression of a yfiD ::lac reporter fusion is enhanced up to 35-fold during acidic growth. The anaerobic transcription factor FNR was confirmed as the major regulator of yfiD expression, and ArcA was found to enhance anaerobic yfiD expression, probably by displacing a repressing FNR dimer in the N935 region of the promoter. Moreover, the pyruvate sensor PdhR was shown to act as a minor anaerobic repressor of yfiD expression. On the basis of its strong homology to the C-terminal region of pyruvate formate-lyase (PFL) it was predicted that YfiD would be a radicalcontaining enzyme. The YfiD radical was found to be introduced by the PFLactivase enzyme, but unlike PFL, AdhE did not deactivate radicalized YfiD. The extent of radical activation of YfiD was enhanced by low intracellular pH, and thus it was concluded that both yfiD expression and YfiD activity are affected by growth at low pH. The yfiD mutant strain JRG4033 excreted increased levels of organic acids compared to the parental strain when grown in chemostat culture under oxygen-starved conditions, consistent with the acid-inducibility of yfiD expression and the recently reported ability of YfiD to rescue the activity of oxygenolytically cleaved PFL.

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“…The pH apparently has little influence, but high salt or sugar concentrations and low water contents, exert very strong baro-protective effects. Many other articles have also dealt with the stability of proteins as a function of pressure (Zagrobelny and Bright, 1992;Athes et al, 1998) and particularly with that of enzymes (Degraeve and Lemay, 1997;Degraeve et al, 1996;Mozhaev et al, 1996;Marie-Olive et al, 2000).…”

Section: The Effect Of High Pressure and Temperature On Food Constitumentioning

confidence: 98%

Research Activities on Supercritical Fluid Science in Food Biotechnology

Khosravi‐Darani

2010

Critical Reviews in Food Science and Nutrition

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This article serves as an overview, introducing the currently popular area of supercritical fluids and their uses in food biotechnology. Within each application, and wherever possible, the basic principles of the technique, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, non-supercritical methods are given. Most current commercial application of the supercritical extraction involve biologically-produced materials; the technique may be particularly relevant to the extraction of biological compounds in cases where there is a requirement for low-temperature processing, high mass-transfer rates, and negligible carrying over of the solvent into the final product. Special applications to food processing include the decaffeination of green coffee beans, the production of hops extracts, the recovery of aromas and flavors from herbs and spices, the extraction and fractionation of edible oils, and the removal of contaminants, among others. New advances, in which the extraction is combined with reaction or crystallization steps, may further increase the attractiveness of supercritical fluids in the bioprocess industries. To develop and establish a novel and effective alternative to heating treatment, the lethal action of high hydrostatic pressure CO(2) on microorganisms, with none or only a minimal heating process, has recently received a great deal of attention.

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Pressure-induced inactivation of E. coli β-galactosidase: influence of pH and temperatur

Cited by 27 publications

References 25 publications

Gonococcal Genes Encoding Transferrin-Binding Proteins A and B Are Arranged in a Bicistronic Operon but Are Subject to Differential Expression

Gonococcal Genes Encoding Transferrin-Binding Proteins A and B Are Arranged in a Bicistronic Operon but Are Subject to Differential Expression

Expression of the Escherichia coli yfiD gene responds to intracellular pH and reduces the accumulation of acidic metabolic end products

Research Activities on Supercritical Fluid Science in Food Biotechnology

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