Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Bond, Daniel R.; Russell, James B.

doi:10.1099/00221287-146-3-687

Cited by 19 publications

(12 citation statements)

References 35 publications

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“…This increase in driving force available to the ATPase was consistent with an increase in ⌬p (-80 to -140 mV). The relationship between ⌬p and the rate of energy spilling was clearly non-ohmic, and the 'leak' of protons through the cell membrane seemed to have a threshold of approximately -80 mV [Bond and Russell, 2000].…”

Section: How Is the Energy Spilling Of S Bovis Regulated?mentioning

confidence: 99%

“…Because a mutant which was defective in high-affinity potassium transport utilized glucose more efficiently [Buurman et al, 1991], it appeared that the wild type was taking up potassium by the highaffinity, ATP-driven (Kdp) system and losing potassium on the low-affinity, proton symport (Trk) system. Because the energy spilling of S. bovis was neither potassium nor sodium-dependent, the energy spilling reaction of S. bovis could not be explained by a similar mechanism [Bond and Russell, 2000].…”

Section: Do Other Bacteria Spill Energy?mentioning

confidence: 99%

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The Energy Spilling Reactions of Bacteria and Other Organisms

Russell¹

2007

Microb Physiol

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For many years it was assumed that living organisms always utilized ATP in a highly efficient manner, but simple growth studies with bacteria indicated that the efficiency of biomass production was often at least 3-fold lower than the amount that would be predicted from standard biosynthetic pathways. The utilization of energy for maintenance could only explain a small portion of this discrepancy particularly when the growth rate was high. These ideas and thermodynamic arguments indicated that cells might have another avenue of energy utilization. This phenomenon has also been called ‘uncoupling’, ‘spillage’ and ‘overflow metabolism’, but ‘energy spilling’ is probably the most descriptive term. It appears that many bacteria spill energy, and the few that do not can be killed (large and often rapid decrease in viability), if the growth medium is nitrogen-limited and the energy source is in ‘excess’. The lactic acid bacterium, Streptococcus bovis, is an ideal bacterium for the study of energy spilling. Because it only uses substrate level phosphorylation to generate ATP, ATP generation can be calculated with a high degree of certainty. It does not store glucose as glycogen, and its cell membrane can be easily accessed. Comparative analysis of heat production, membrane voltage, ATP production and Ohm’s law indicated that the energy spilling reaction of S. bovis is mediated by a futile cycle of protons through the cell membrane. Less is known about Escherichia coli, but in this bacterium energy spilling could be mediated by a futile cycle of potassium or ammonium ions. Energy spilling is not restricted to prokaryotes and appears to occur in yeasts and in higher organisms. In man, energy spilling may be related to cancer, ageing, ischemia and cardiac failure.

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Section: How Is the Energy Spilling Of S Bovis Regulated?mentioning

confidence: 99%

Section: Do Other Bacteria Spill Energy?mentioning

confidence: 99%

The Energy Spilling Reactions of Bacteria and Other Organisms

Russell¹

2007

Microb Physiol

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179

130

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“…A metabolic flux analysis of E. coli predicted that excess of carbon and energy might cause over-flow metabolism, which results in less efficient carbon utilization and decreased growth [57]. In Streptococcus bovis , excess ATP generation can cause ‘energy spilling’ by futile cycling of protons through the membrane, which leads to lesser biomass production [58,59]. Whether reductive stress or ‘energy spilling’ take place in a glucose-exposed hexR mutant of P. syringae remains to be analyzed in future studies.…”

Section: Discussionmentioning

confidence: 99%

Expression of extra-cellular levansucrase in Pseudomonas syringae is controlled by the in planta fitness-promoting metabolic repressor HexR

et al. 2015

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BackgroundPseudomonas syringae pv. glycinea PG4180 causes bacterial blight on soybean plants and enters the leaf tissue through stomata or open wounds, where it encounters a sucrose-rich milieu. Sucrose is utilized by invading bacteria via the secreted enzyme, levansucrase (Lsc), liberating glucose and forming the polyfructan levan. P. syringae PG4180 possesses two functional lsc alleles transcribed at virulence-promoting low temperatures.ResultsWe hypothesized that transcription of lsc is controlled by the hexose metabolism repressor, HexR, since potential HexR binding sites were identified upstream of both lsc genes. A hexR mutant of PG4180 was significantly growth-impaired when incubated with sucrose or glucose as sole carbon source, but exhibited wild type growth when arabinose was provided. Analyses of lsc expression resulted in higher transcript and protein levels in the hexR mutant as compared to the wild type. The hexR mutant’s ability to multiply in planta was reduced. HexR did not seem to impact hrp gene expression as evidenced by the hexR mutant’s unaltered hypersensitive response in tobacco and its unmodified protein secretion pattern as compared to the wild type under hrp-inducing conditions.ConclusionsOur data suggested a co-regulation of genes involved in extra-cellular sugar acquisition with those involved in intra-cellular energy-providing metabolic pathways in P. syringae.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0349-0) contains supplementary material, which is available to authorized users.

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“…Thus, microorganisms in the airborne state undergo signi®cant changes in their surface potential. Bacterial cells depend on their membrane potentials for their basic metabolic activity (Cevc, 1990), and alterations in the membrane potential have been shown to signi®cantly aect ion transporters/channels and metabolically essential proteins, such as ATPase (Bond and Russel, 2000;Elinder and Arhem, 1999). Therefore, it is likely that the electric charging aects the membrane potential of sensitive microorganisms so signi®cantly that their cells, especially those that are already injured, become nonviable.…”

Section: Possible Causes Of Inactivation Of Bacteria By High Electricmentioning

confidence: 98%

Effect of electrical charges and fields on injury and viability of airborne bacteria

Mainelis

Górny

Reponen

et al. 2002

Biotech & Bioengineering

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In this study, the effects of the electric charges and fields on the viability of airborne microorganisms were investigated. The electric charges of different magnitude and polarity were imparted on airborne microbial cells by a means of induction charging. The airborne microorganisms carrying different electric charge levels were then extracted by an electric mobility analyzer and collected using a microbial sampler. It was found that the viability of Pseudomonas fluorescens bacteria, used as a model for sensitive bacteria, carrying a net charge from 4100 negative to 30 positive elementary charges ranged between 40% and 60%; the viability of the cells carrying >2700 positive charges was below 1.5%. In contrast, the viability of the stress-resistant spores of Bacillus subtilis var. niger (used as simulant of anthrax-causing Bacillus anthracis spores when testing bioaerosol sensors in various studies), was not affected by the amount of electric charges on the spores. Because bacterial cells depend on their membrane potential for basic metabolic activities, drastic changes occurring in the membrane potential during aerosolization and the local electric fields induced by the imposed charges appeared to affect the sensitive cells' viability. These findings facilitate applications of electric charging for environmental control purposes involving sterilization of bacterial cells by imposing high electric charges on them. The findings from this study can also be used in the development of new bioaerosol sampling methods based on electrostatic principles.

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Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Cited by 19 publications

References 35 publications

The Energy Spilling Reactions of Bacteria and Other Organisms

The Energy Spilling Reactions of Bacteria and Other Organisms

Expression of extra-cellular levansucrase in Pseudomonas syringae is controlled by the in planta fitness-promoting metabolic repressor HexR

Effect of electrical charges and fields on injury and viability of airborne bacteria

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