Ions in the Deep Subsurface of Earth, Mars, and Icy Moons: Their Effects in Combination with Temperature and Pressure on tRNA–Ligand Binding

The interactions of ligands with nucleic acids are central to numerous reactions in the biological cell. How such reactions are affected by harsh environmental conditions such as low temperatures, high pressures, and high concentrations of destructive ions is still largely unknown. To elucidate the ions’ role in shaping habitability in extraterrestrial environments and the deep subsurface of Earth with respect to fundamental biochemical processes, we investigated the effect of selected salts (MgCl2, MgSO4, and Mg(ClO4)2) and high hydrostatic pressure (relevant for the subsurface of that planet) on the complex formation between tRNA and the ligand ThT. The results show that Mg2+ salts reduce the binding tendency of ThT to tRNA. This effect is largely due to the interaction of ThT with the salt anions, which leads to a strong decrease in the activity of the ligand. However, at mM concentrations, binding is still favored. The ions alter the thermodynamics of binding, rendering complex formation that is more entropy driven. Remarkably, the pressure favors ligand binding regardless of the type of salt. Although the binding constant is reduced, the harsh conditions in the subsurface of Earth, Mars, and icy moons do not necessarily preclude nucleic acid–ligand interactions of the type studied here.

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High pressures increase α-chymotrypsin enzyme activity under perchlorate stress

Communications Biology ◽

10.1038/s42003-020-01279-4 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Stewart Gault ◽

Michel W. Jaworek ◽

Roland Winter ◽

Charles S. Cockell

Keyword(s):

High Pressure ◽

Enzyme Activity ◽

Phase Space ◽

High Pressures ◽

Extreme Environments ◽

Combined Effects ◽

Deep Subsurface ◽

Subsurface Environments ◽

Dissolved Ions ◽

High Concentrations

Abstract Deep subsurface environments can harbour high concentrations of dissolved ions, yet we know little about how this shapes the conditions for life. We know even less about how the combined effects of high pressure influence the way in which ions constrain the possibilities for life. One such ion is perchlorate, which is found in extreme environments on Earth and pervasively on Mars. We investigated the interactions of high pressure and high perchlorate concentrations on enzymatic activity. We demonstrate that high pressures increase α-chymotrypsin enzyme activity even in the presence of high perchlorate concentrations. Perchlorate salts were shown to shift the folded α-chymotrypsin phase space to lower temperatures and pressures. The results presented here may suggest that high pressures increase the habitability of environments under perchlorate stress. Therefore, deep subsurface environments that combine these stressors, potentially including the subsurface of Mars, may be more habitable than previously thought.

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Effects of temperatures and high pressures on the growth and survivability of methanogens and stable carbon isotope fractionation: implications for deep subsurface life on Mars

International Journal of Astrobiology ◽

10.1017/s1473550418000216 ◽

2018 ◽

pp. 1-7

Author(s):

Navita Sinha ◽

Sudip Nepal ◽

Timothy Kral ◽

Pradeep Kumar

Keyword(s):

Methane Concentration ◽

High Pressures ◽

Stable Carbon Isotope ◽

Isotopic Fractionation ◽

Methanogenic Archaea ◽

Stable Carbon ◽

Isotopic Data ◽

Deep Subsurface ◽

Carbon Isotopic ◽

Temperature And Pressure

AbstractIn order to examine the potential survivability of life in the Martian deep subsurface, we have investigated the effects of temperature (45°C, 55°C and 65°C) and pressure (1, 400, 800 and 1200 atm) on the growth, carbon isotopic data and morphology of chemolithoautotrophic anaerobic methanogenic archaea,Methanothermobacter wolfeii. The growth and survivability of this methanogen were determined by measuring the methane concentration in headspace gas samples after the cells were returned to their conventional growth conditions. Interestingly, this methanogen survived at all the temperatures and pressures tested.M. wolfeiidemonstrated the highest methane concentration following exposure to pressure of 800 atm and a temperature of 65°C. We found that the stable carbon isotopic fractionation of methane, δ13C(CH4), was slightly more enriched in12C at 1 atm and 55°C than the carbon isotopic data obtained in other temperature and pressure conditions. A comparison of the images of the cells before and after the exposure to different temperatures and pressures did not show any obvious alteration in the morphology ofM. wolfeii. The research reported here suggests that at least one methanogen,M. wolfeii, may be able to survive under hypothetical Martian subsurface conditions with respect to temperature and pressure.

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Effects of Temperatures and High Pressures on the Growth and Survivability of Methanogens and Stable Carbon Isotope Fractionation: Implications for Deep Subsurface Life on Mars

10.1101/281105 ◽

2018 ◽

Author(s):

Navita Sinha ◽

Sudip Nepal ◽

Timothy Kral ◽

Pradeep Kumar

Keyword(s):

Methane Concentration ◽

High Pressures ◽

Stable Carbon Isotope ◽

Isotopic Fractionation ◽

Methanogenic Archaea ◽

Stable Carbon ◽

Isotopic Data ◽

Deep Subsurface ◽

Carbon Isotopic ◽

Temperature And Pressure

AbstractIn order to examine the potential survivability of life in the Martian deep subsurface, we have investigated the effects of temperature (45°C, 55°C, and 65°C) and pressure (1 atm, 400 atm, 800 atm, and 1200 atm) on the growth, carbon isotopic data, and morphology of chemolithoautotrophic anaerobic methanogenic archaea,Methanothermobacter wolfeii. The growth and survivability of this methanogen were determined by measuring the methane concentration in headspace gas samples after the cells were returned to their conventional growth conditions. Interestingly, this methanogen survived at all the temperatures and pressures tested.M. wolfeiidemonstrated the highest methane concentration following exposure to pressure of 800 atm and a temperature of 65°C. We found that the stable carbon isotopic fractionation of methane, δ13C(CH4), was slightly more enriched in12C at 1 atm and 55°C than the carbon isotopic data obtained in other temperature and pressure conditions. A comparison of the images of the cells before and after the exposure to different temperatures and pressures did not show any obvious alteration in the morphology ofM. wolfeii. The research reported here suggests that at least one methanogen,M. wolfeii, may be able to survive under hypothetical Martian subsurface conditions with respect to temperature and pressure.

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Conformational dynamics and thermodynamics of protein–ligand binding studied by NMR relaxation

Biochemical Society Transactions ◽

10.1042/bst20110750 ◽

2012 ◽

Vol 40 (2) ◽

pp. 419-423 ◽

Cited By ~ 46

Author(s):

Mikael Akke

Keyword(s):

Ligand Binding ◽

Bound States ◽

Conformational Dynamics ◽

Nmr Relaxation ◽

Titration Calorimetry ◽

Conformational Entropy ◽

Chain Order ◽

Ligand Interactions ◽

Galectin 3 ◽

Relaxation Experiments

Protein conformational dynamics can be critical for ligand binding in two ways that relate to kinetics and thermodynamics respectively. First, conformational transitions between different substates can control access to the binding site (kinetics). Secondly, differences between free and ligand-bound states in their conformational fluctuations contribute to the entropy of ligand binding (thermodynamics). In the present paper, I focus on the second topic, summarizing our recent results on the role of conformational entropy in ligand binding to Gal3C (the carbohydrate-recognition domain of galectin-3). NMR relaxation experiments provide a unique probe of conformational entropy by characterizing bond-vector fluctuations at atomic resolution. By monitoring differences between the free and ligand-bound states in their backbone and side chain order parameters, we have estimated the contributions from conformational entropy to the free energy of binding. Overall, the conformational entropy of Gal3C increases upon ligand binding, thereby contributing favourably to the binding affinity. Comparisons with the results from isothermal titration calorimetry indicate that the conformational entropy is comparable in magnitude to the enthalpy of binding. Furthermore, there are significant differences in the dynamic response to binding of different ligands, despite the fact that the protein structure is virtually identical in the different protein–ligand complexes. Thus both affinity and specificity of ligand binding to Gal3C appear to depend in part on subtle differences in the conformational fluctuations that reflect the complex interplay between structure, dynamics and ligand interactions.

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Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

Functional Plant Biology ◽

10.1071/fp15302 ◽

2016 ◽

Vol 43 (4) ◽

pp. 324 ◽

Cited By ~ 15

Author(s):

Supriya Tiwari ◽

Rüdiger Grote ◽

Galina Churkina ◽

Tim Butler

Keyword(s):

Stomatal Conductance ◽

Environmental Conditions ◽

Economic Losses ◽

Plant Responses ◽

Damage Scenarios ◽

Biochemical Processes ◽

Wide Range ◽

Defence Responses ◽

High Concentrations ◽

The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

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Pressure dependent low temperature kinetics for CN + CH3CN: competition between chemical reaction and van der Waals complex formation

Physical Chemistry Chemical Physics ◽

10.1039/c6cp01982j ◽

2016 ◽

Vol 18 (22) ◽

pp. 15118-15132 ◽

Cited By ~ 14

Author(s):

Chantal Sleiman ◽

Sergio González ◽

Stephen J. Klippenstein ◽

Dahbia Talbi ◽

Gisèle El Dib ◽

...

Keyword(s):

Low Temperature ◽

Complex Formation ◽

Gas Phase ◽

Rate Coefficient ◽

Flow Reactor ◽

Slow Flow ◽

Phase Reaction ◽

Gas Phase Reaction ◽

Low Temperature Kinetics ◽

Temperature And Pressure

The gas phase reaction between the CN radical and acetonitrile CH3CN was investigated experimentally with a CRESU apparatus and a slow flow reactor as well as theoretically to explore the temperature and pressure dependence of its rate coefficient from 354 K down to 23 K.

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Design of an LTCC Structure for a Micro-Ceramic Combustor

Additional Conferences (Device Packaging HiTEC HiTEN & CICMT) ◽

10.4071/cicmt-2012-wa14 ◽

2012 ◽

Vol 2012 (CICMT) ◽

pp. 000288-000293

Author(s):

Darko Belavic ◽

Marko Hrovat ◽

Gregor Dolanc ◽

Kostja Makarovic ◽

Marina Santo Zarnik ◽

...

Keyword(s):

High Pressures ◽

Three Dimensional ◽

Ceramic Technology ◽

Electronic Components ◽

Buried Structures ◽

Flow Rates ◽

Points Of View ◽

Micro Systems ◽

Micro Combustor ◽

Harsh Conditions

Advanced micro- or macro-systems are in some cases made with multilayer ceramic technology. Low-Temperature Co-fired Ceramic (LTCC) technology is considered as one of the more suitable technologies for the fabrication of ceramic micro-systems that integrate screen-printed, thick-film electronic components as well as three-dimensional buried structures, for example, cavities and channels. One of the applications is a ceramic combustor. The chemical energy of the fuel is converted into thermal energy in a chemical micro-combustor through a burning process, while the accompanying high temperatures and, frequently, high pressures impose harsh conditions on the combustor structure. Therefore, the combustor must be carefully designed not only from the functional, thermal and chemical points of view, but also with respect to the mechanical strength. The combustor device was prepared by laminating of Du Pont 951PX LTCC green tapes. The fabricated 3D LTCC structures with buried cavities and channels including two inlets (for fuel and air), the evaporator for the fuel, the mixing system of the channels (for mixing the evaporated fuel and air), the distribution channels and eight microburners were realized. The main parts are eight micro-burners realized as buried cavities. In the burners a platinum-based catalyst was deposited to assist the oxidation, i.e., the burning, of the methanol with the air. Thickfilm, platinum-based heaters and temperature sensors are incorporated within the structure. The device was tested with different flow rates of liquid methanol (1 ml/h to 5 ml/h) and air (7 l/h to 15 l/h). The obtained temperatures were between 250°C and 450°C.

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Design and Fabrication of an LTCC Structure for a Microceramic Combustor

Journal of Microelectronics and Electronic Packaging ◽

10.4071/imaps.342 ◽

2012 ◽

Vol 9 (3) ◽

pp. 120-125 ◽

Cited By ~ 2

Author(s):

Darko Belavic ◽

Marko Hrovat ◽

Gregor Dolanc ◽

Kostja Makarovic ◽

Marina Santo Zarnik

Keyword(s):

Thick Film ◽

High Pressures ◽

Three Dimensional ◽

Temperature Sensors ◽

Ceramic Technology ◽

Electronic Components ◽

Buried Structures ◽

Flow Rates ◽

Points Of View ◽

Harsh Conditions

Advanced microsystems or macrosystems are in some cases made with multilayer ceramic technology. Low-temperature cofired ceramic (LTCC) technology is considered to be one of the more suitable technologies for the fabrication of ceramic microsystems that integrate screen-printed, thick-film electronic components as well as three-dimensional buried structures, for example, cavities and channels. One of the applications is a ceramic combustor. The chemical energy of the fuel is converted into thermal energy in a chemical microcombustor through a burning process, while the accompanying high temperatures and, frequently, high pressures, impose harsh conditions on the combustor structure. Therefore, the combustor must be carefully designed not only from the functional, thermal, and chemical points of view, but also with respect to the mechanical strength. The combustor device was prepared by lamination of Du Pont 951PX LTCC green tapes. The fabricated 3D LTCC structures with buried cavities and channels including two inlets (for fuel and air), the evaporator for the fuel, the mixing system of the channels (for mixing the evaporated fuel and air), the distribution channels and eight microburners were realized. The main parts are eight microburners realized as buried cavities. In the burners, a platinum-based catalyst was deposited to assist the oxidation, that is, the burning, of the methanol with the air. Thick-film, platinum-based heaters and temperature sensors are incorporated within the structure. The device was tested with different flow rates of liquid methanol (1 mL/h to 5 mL/h) and air (7 L/h to 15 L/h). The temperatures obtained were between 250°C and 450°C.

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