Factors affecting the cation requirement of a halophilic NADH dehydrogenase

Houchstein, Lawrence I.; Dalton, Bonnie P.

doi:10.1016/0005-2744(68)90062-4

Cited by 15 publications

(5 citation statements)

References 6 publications

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“…Enzyme activity of purified enzyme is higher with KCl than with NaCl at equimolar concentrations ; the opposite has previously been generally found to be true [l] and crude cell-free extracts did generally exhibit higher ornithine carbamoyltransferase activity in the presence of KC1 than in equimolar concentrations of NaC1. Rubidium chloride and cesium chloride have previously been shown to be able to substitute for NaCl with a halophilic NADH oxidase [16] but while that enzyme did exhibit some activity when LiCl substituted for NaC1, the purified ornithine carbamoyltransferase was completely inactive at all LiCl concentrations, no activity being detected even when enzyme concentrations were increased 10-fold above that utilized with NaC1.…”

Section: Discussionmentioning

confidence: 94%

Ornithine Carbamoyltransferase from Halobacterium salinarium

Dundas¹

1972

Eur J Biochem

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The enzymatic properties of purified ornithine carbamoyltransferase from Halobacterium salinarium have been studied and compared with those of the enzyme from non-halophilic organisms, and with those of other enzymes from halophilic organisms.The enzyme is stable and active in high concentrations of NaCl, KC1, RbCl and CsCl as are other enzymes from halophilic organisms. No activity could be measured a t any concentrations of LiCl. The pH optimum for activity is similar for ornithine carbamoyltransferase from halophilic and nonhalophilic organisms. The enzyme is effectively protected against denaturation by the presence of any of its substrates, ornithine, citrulline or carbamoylphosphate, a phenomenon found for many enzymes from non-halophilic organisms. Ornithine carbamoyltransferase from H . salinarium shows a cooperative effect in binding ornithine, similar allosteric effects are found for the enzyme from non-halophilic organisms. Phosphate inhibits enzyme activity competitively versus carbamoylphosphate for enzymes from both halophilic and non-halophilic organisms.Ornithine carbamoyltransferase from H . salinarium accordingly seems to be subject to control mechanisms similar to those operative for the non-halophilic enzyme. There is no evidence that unusual or specific controls are operative for the enzyme in high salt concentrations. The unique properties of the halophilic enzyme are related only to its ability to function a t high salt concentrations.Halobacteria grow only in media containing 12 to 20°/, NaCl and many strains are able to proliferate in media with near saturation concentrations of NaC1. Enzymes from Halobacteria have adapted to the very high intercellular concentrations of salts in the organisms and are rapidly inactivated in the absence of salt. Many of these enzymes show optimal activities in the presence of NaCl concentrations higher than 3 M [l].

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Section: Discussionmentioning

confidence: 94%

Ornithine Carbamoyltransferase from Halobacterium salinarium

Dundas¹

1972

Eur J Biochem

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“…Yet due to complex ion-specific interactions both with the solvent and directly with biomolecules, there is a strong rationale to expect that brines of different compositions will exert different stresses on microorganisms. Indeed, many studies of both halophiles and their biomolecules have shown that changing the ionic composition of the milieu can influence every aspect of biological function, including protein conformation, enzymatic activity, cellular morphology, growth rate and culture density (e.g., Flannery, 1956 ; Abram and Gibbons, 1961 ; Boring et al, 1963 ; Houchstein and Dalton, 1968 ; Lanyi, 1974 ; Madern et al, 2000 ). Many of these historical studies, whilst they suggest important ion-specific effects, do not account for variations in water activity across different salt solutions, thus making discrimination between ion-specific and hydration-related effects difficult.…”

Section: Introductionmentioning

confidence: 99%

Building a Geochemical View of Microbial Salt Tolerance: Halophilic Adaptation of Marinococcus in a Natural Magnesium Sulfate Brine

Fox-Powell

Cockell

2018

Front. Microbiol.

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Current knowledge of life in hypersaline habitats is mostly limited to sodium and chloride-dominated environments. This narrow compositional window does not reflect the diversity of brine environments that exist naturally on Earth and other planetary bodies. Understanding the limits of the microbial biosphere and predicting extraterrestrial habitability demands a systematic effort to characterize ionic specificities of organisms from a representative range of saline habitats. Here, we investigated a strain of Marinococcus isolated from the magnesium and sulfate-dominated Basque Lakes (British Columbia, Canada). This organism was the sole isolate obtained after exposure to exceptionally high levels of Mg2+ and SO42- ions (2.369 and 2.840 M, respectively), and grew at extremes of ionic strength not normally encountered in Na+/Cl- brines (12.141 mol liter-1). Its association at the 16S rDNA level with bacterial halophiles suggests that ancestral halophily has allowed it to adapt to a different saline habitat. Growth was demonstrated in media dominated by NaCl, Na2SO4, MgCl2, and MgSO4, yet despite this plasticity the strain was still restricted; requiring either Na+ or Cl- to maintain short doubling times. Water activity could not explain growth rate differences between media, demonstrating the importance of ionic composition for dictating microbial growth windows. A new framework for understanding growth in brines is required, that accounts for the geochemical history of brines as well as the various stresses that ions impose on microbes. Studies such as this are required to gain a truly universal understanding of the limits of biological ion tolerance.

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“…The total bulk protein in halophilic cells (101) as well as membrane proteins (72,92,110,113) and ribosomal proteins (9,122) contain a large excess of acidic amino acids. In some cases low concentrations of MgC12 or CaCl2 can substitute, at least partly, for high concentrations of monovalent salts (25,54,55,76,83,96). Finally, Brown showed that succinylation of membranes of marine bacteria increased their halophilic character (22).…”

Section: Introductionmentioning

confidence: 99%

Salt-dependent properties of proteins from extremely halophilic bacteria.

Lanyi¹

1974

Bacteriological Reviews

433

222

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113 69 a Hydrophobicity index (in kcal/residue) calculated as described by Bigelow (14), who used the free energies of transfer for amino acids from water to ethanol (118). Ratio of volume for polar and nonpolar residues, according to Fisher (41). cDialysis of ribosomes against buffer containing Mg'+, and a low concentration of monovalent cations, followed by sedimenting the RNA-rich particles. dDialysis of ribosomes against 0.3 mM Mg2+, centrifugation; supernatant is S-1. Incubation in 3.5 M LiCl-ethylenediaminetetraacetic acid (EDTA), centrifugation. Supernatant is S-2, followed by incubation in 3.5 M LiCl-urea, which yielded supernatant S-3. ' Cell envelopes were dialyzed against 0.01 M EDTA. Centrifugation at 105,000 x g yielded red pellet (J. K. Lanyi and E. L. Bugna, unpublished data). ' Exhaustive dialysis of cell membranes against distilled water, sedimentation at 105,000 x g for 20 to 30 h.

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Factors affecting the cation requirement of a halophilic NADH dehydrogenase

Cited by 15 publications

References 6 publications

Ornithine Carbamoyltransferase from Halobacterium salinarium

Ornithine Carbamoyltransferase from Halobacterium salinarium

Building a Geochemical View of Microbial Salt Tolerance: Halophilic Adaptation of Marinococcus in a Natural Magnesium Sulfate Brine

Salt-dependent properties of proteins from extremely halophilic bacteria.

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