Temperature Dependence Of Interaction Research Articles

Comparison of Sucrose and Trehalose for Protein Stabilization Using Differential Scanning Calorimetry.

The disaccharide trehalose is generally acknowledged as a superior stabilizer of proteins and other biomolecules in aqueous environments. Despite many theories aiming to explain this, the stabilization mechanism is still far from being fully understood. This study compares the stabilizing properties of trehalose with those of the structurally similar disaccharide sucrose. The stability has been evaluated for the two proteins, lysozyme and myoglobin, at both low and high temperatures by determining the glass transition temperature, Tg, and the denaturation temperature, Tden. The results show that the sucrose-containing samples exhibit higher Tden than the corresponding trehalose-containing samples, particularly at low water contents. The better stabilizing effect of sucrose at high temperatures may be explained by the fact that sucrose, to a greater extent, binds directly to the protein surface compared to trehalose. Both sugars show Tden elevation with an increasing sugar-to-protein ratio, which allows for a more complete sugar shell around the protein molecules. Finally, no synergistic effects were found by combining trehalose and sucrose. Conclusively, the exact mechanism of protein stabilization may vary with the temperature, as influenced by temperature-dependent interactions between the protein, sugar, and water. This variability can make trehalose to a superior stabilizer under some conditions and sucrose under others.

Phosphatidylinositol-4,5-biphosphate (PIP2)-Dependent Thermoring Basis for Cold-Sensing of the Transient Receptor Potential Melastatin-8 (TRPM8) Biothermometer

The menthol sensor transient receptor potential melastatin-8 (TRPM8) can be activated by cold and, thus, serves as a biothermometer in a primary afferent sensory neuron for innocuous-to-noxious cold detection. However, the precise structural origins of specific temperature thresholds and sensitivity have remained elusive. Here, a grid thermodynamic model was employed, to examine if the temperature-dependent noncovalent interactions found in the 3-dimensional (3D) structures of thermo-gated TRPM8 could assemble into a well-organized fluidic grid-like mesh network, featuring the constrained grids as the thermorings for cold-sensing in response to PIP2, Ca2+ and chemical agents. The results showed that the different interactions of TRPM8 with PIP2 during the thermal incubation induced the formation of the biggest grids with distinct melting temperature threshold ranges. Further, the overlapped threshold ranges between open and pre-open closed states were required for initial cold activation with the matched thermo-sensitivity and the decrease in the systematic thermal instability. Finally, the intact anchor grid near the lower gate was important for channel opening with the active selectivity filter. Thus, PIP2-dependent thermorings in TRPM8 may play a pivotal role in cold sensing.

Three-Dimensional Optothermal Manipulation of Light-Absorbing Particles in Phase-Change Gel Media.

Rational manipulation and assembly of discrete colloidal particles into architected superstructures have enabled several applications in materials science and nanotechnology. Optical manipulation techniques, typically operated in fluid media, facilitate the precise arrangement of colloidal particles into superstructures by using focused laser beams. However, as the optical energy is turned off, the inherent Brownian motion of the particles in fluid media impedes the retention and reconfiguration of such superstructures. Overcoming this fundamental limitation, we present on-demand, three-dimensional (3D) optical manipulation of colloidal particles in a phase-change solid medium made of surfactant bilayers. Unlike liquid crystal media, the lack of fluid flow within the bilayer media enables the assembly and retention of colloids for diverse spatial configurations. By utilizing the optically controlled temperature-dependent interactions between the particles and their surrounding media, we experimentally exhibit the holonomic microscale control of diverse particles for repeatable, reconfigurable, and controlled colloidal arrangements in 3D. Finally, we demonstrate tunable light-matter interactions between the particles and 2D materials by successfully manipulating and retaining these particles at fixed distances from the 2D material layers. Our experimental results demonstrate that the particles can be retained for over 120 days without any change in their relative positions or degradation in the bilayers. With the capability of arranging particles in 3D configurations with long-term stability, our platform pushes the frontiers of optical manipulation for distinct applications such as metamaterial fabrication, information storage, and security.

Modulating Phase Behavior in Fatty Acid-Modified Elastin-like Polypeptides (FAMEs): Insights into the Impact of Lipid Length on Thermodynamics and Kinetics of Phase Separation.

Although post-translational lipidation is prevalent in eukaryotes, its impact on the liquid-liquid phase separation of disordered proteins is still poorly understood. Here, we examined the thermodynamic phase boundaries and kinetics of aqueous two-phase system (ATPS) formation for a library of elastin-like polypeptides modified with saturated fatty acids of different chain lengths. By systematically altering the physicochemical properties of the attached lipids, we were able to correlate the molecular properties of lipids to changes in the thermodynamic phase boundaries and the kinetic stability of droplets formed by these proteins. We discovered that increasing the chain length lowers the phase separation temperature in a sigmoidal manner due to alterations in the unfavorable interactions between protein and water and changes in the entropy of phase separation. Our kinetic studies unveiled remarkable sensitivity to lipid length, which we propose is due to the temperature-dependent interactions between lipids and the protein. Strikingly, we found that the addition of just a single methylene group is sufficient to allow tuning of these interactions as a function of temperature, with proteins modified with C7-C9 lipids exhibiting non-Arrhenius dependence in their phase separation, a behavior that is absent for both shorter and longer fatty acids. This work advances our theoretical understanding of protein-lipid interactions and opens avenues for the rational design of lipidated proteins in biomedical paradigms, where precise control over the phase separation is pivotal.

Elucidation of temperature-induced water structuring on cellulose surfaces for environmental and energy sustainability

Optimizing drying energy in the forest products industry is critical for integrating lignocellulosic feedstocks across all manufacturing sectors. Despite substantial efforts to reduce thermal energy consumption during drying, further enhancements are possible. Cellulose, the main component of forest products, is Earth's most abundant biopolymer and a promising renewable feedstock. This study employs all-atom molecular dynamics (MD) simulations to explore the structural dynamics of a small Iβ-cellulose microcrystallite and surrounding water layers during drying. Molecular and atomistic profiles revealed localized water near the cellulose surface, with water structuring extending beyond 8 Å into the water bulk, influencing solvent-accessible surface area and solvation energy. With increasing temperature, there was a ∼20 % reduction in the cellulose surface available for interaction with water molecules, and a ∼22 % reduction in solvation energy. The number of hydrogen bonds increased with thicker water layers, facilitated by a “bridging” effect. Electrostatic interactions dominated the intermolecular interactions at all temperatures, creating an energetic barrier that hinders water removal, slowing the drying processes. Understanding temperature-dependent cellulose-water interactions at the molecular level will help in designing novel strategies to address drying energy consumption, advancing the adoption of lignocellulosics as viable manufacturing feedstocks.

In Vitro Determination of Temperature-Dependent DNA Binding of the Evening Complex Using Electrophoretic Mobility Shift Assays.

Electrophoretic mobility shift assays (EMSAs) of DNA-binding proteins and labeled DNA allow the qualitative and quantitative characterization of protein-DNA complex formation using native (nondenaturing) polyacrylamide or agarose gel electrophoresis. By varying the incubation temperature of the protein-DNA binding reaction and maintaining this temperature during electrophoresis, temperature-dependent protein-DNA interactions can be investigated. Here, we provide examples of the binding of a transcriptional repressor complex called the Evening Complex, comprising the DNA-binding protein LUX ARRYTHMO (LUX), the scaffold protein EARLY FLOWERING 3 (ELF3), and the adapter protein ELF4, to its cognate DNA and demonstrate direct detection and visualization of thermoresponsive binding in vitro. As negative controls we use the LUX DNA-binding domain and LUX full length protein, which do not exhibit temperature-dependent DNA binding.

Thermoring basis for the TRPV3 bio-thermometer

The thermosensitive transient receptor potential (TRP) channels are well-known as bio-thermometers with specific temperature thresholds and sensitivity. However, their precise structural origins are still mysterious. Here, graph theory was used to test how the temperature-dependent non-covalent interactions as identified in the 3D structures of thermo-gated TRPV3 could form a systematic fluidic grid-like mesh network with the constrained thermo-rings from the biggest grids to the smallest ones as necessary structural motifs for the variable temperature thresholds and sensitivity. The results showed that the heat-evoked melting of the biggest grids may control the specific temperature thresholds to initiate channel gating while the smaller grids may be required to secure heat efficacy. Together, all the grids along the lipid-dependent minimal gating pathway may be necessary to change with molar heat capacity for the specific temperature sensitivity. Therefore, this graph theory-based grid thermodynamic model may provide an extensive structural basis for the thermo-gated TRP channels.

Nanocavity enhanced photon coherence of solid-state quantum emitters operating up to 30 K

Solid-state emitters such as epitaxial quantum dots have emerged as a leading platform for efficient, on-demand sources of indistinguishable photons, a key resource for many optical quantum technologies. To maximise performance, these sources normally operate at liquid helium temperatures ( ∼4 K ), introducing significant size, weight and power requirements that can be impractical for proposed applications. Here we experimentally resolve the two distinct temperature-dependent phonon interactions that degrade indistinguishability, allowing us to demonstrate that coupling to a photonic nanocavity can greatly improve photon coherence at elevated temperatures up to 30 K that are compatible with compact cryocoolers. We derive a polaron model that fully captures the temperature-dependent influence of phonons observed in our experiments, providing predictive power to further increase the indistinguishability and operating temperature of future devices through optimised cavity parameters.

Thermoring-based heat activation switches in the TRPV1 biothermometer

Non-covalent interactions in bio-macromolecules are individually weak but collectively important. How they take a concerted action in a complex biochemical reaction network to realize their thermal stability and activity is still challenging to study. Here graph theory was used to investigate how the temperature-dependent non-covalent interactions as identified in the 3D structures of the thermo-gated capsaicin receptor TRPV1 could form a systemic fluidic grid-like mesh network with topological grids constrained as the thermo-rings to govern heat-sensing. The results showed that the heat-evoked melting of the biggest grid initiated a matched temperature threshold to release the lipid from the active vanilloid site for channel activation. Meanwhile, smaller grids were required to stabilize heat efficacy. Altogether, the change in the total grid sizes upon the change in the total noncovalent interactions along the lipid-dependent gating pathway was necessary for the matched temperature sensitivity. Therefore, this grid thermodynamic model may be broadly significant for the structural thermostability and the functional thermoactivity of bio-macromolecules.

Thermal Ring-Based Heat Switches in Hyperthermophilic Class II Bacterial Fructose Aldolase.

Both thermophilic and hyperthermophilic enzymes in bacterial and archaeal species are activated above a specific temperature threshold but inactivated at another higher temperature. However, the underlying structural basis for these two heat switches is still unresolved. Here, graph theory was used to test if the temperature-dependent noncovalent interactions and metal bridges as identified in a series of crystal structures of the class II bacterial fructose 1,6-bisphosphate aldolase homodimer or homotetramer with or without natural substrates and products bound could form systematic fluidic grid-like mesh networks with topological grids as thermal rings to regulate their structural thermostability and functional thermoactivity. The results indicated that the second biggest grid in the Thermus aquaticus fructose 1,6-diphosphate aldolase dimer may control the specific temperature threshold to release the swapping flexible active sites at the dimeric interface for heat-evoked activation. Meanwhile, the third biggest grid may serve as a necessary structural motif against heat inactivation. Finally, the smallest grid may act as a stiff thermostable anchor. Its dissociation at the maximal melting temperature threshold may stop the catalytic activity. Taken as a whole, this computational study may render the structural motifs for the optimal growth temperature and the extreme heat stability of hyperthermophiles.

A Plasmodium membrane receptor platform integrates cues for egress and invasion in blood forms and activation of transmission stages.

Critical events in the life cycle of malaria-causing parasites depend on cyclic guanosine monophosphate homeostasis by guanylyl cyclases (GCs) and phosphodiesterases, including merozoite egress or invasion of erythrocytes and gametocyte activation. These processes rely on a single GCα, but in the absence of known signaling receptors, how this pathway integrates distinct triggers is unknown. We show that temperature-dependent epistatic interactions between phosphodiesterases counterbalance GCα basal activity preventing gametocyte activation before mosquito blood feed. GCα interacts with two multipass membrane cofactors in schizonts and gametocytes: UGO (unique GC organizer) and SLF (signaling linking factor). While SLF regulates GCα basal activity, UGO is essential for GCα up-regulation in response to natural signals inducing merozoite egress and gametocyte activation. This work identifies a GC membrane receptor platform that senses signals triggering processes specific to an intracellular parasitic lifestyle, including host cell egress and invasion to ensure intraerythrocytic amplification and transmission to mosquitoes.

Network Basis for the Heat-Adapted Structural Thermostability of Bacterial Class II Fructose Bisphosphate Aldolase.

The sufficient structural thermostability of a biological macromolecule is an overriding need for green nanoreactors and nanofactories to secure high activity. However, little is still known about what specific structural motif is responsible for it. Here, graph theory was employed to examine if the temperature-dependent noncovalent interactions and metal bridges, as identified in the structures of Escherichia coli class II fructose 1,6-bisphosphate aldolase, could shape a systematic fluidic grid-like mesh network with topological grids to regulate the structural thermostability of the wild-type construct and its evolved variants in each generation upon decyclization. The results indicated that the biggest grids may govern the temperature thresholds for their tertiary structural perturbations but without affecting the catalytic activities. Moreover, lower grid-based systematic thermal instability may facilitate structural thermostability, but a highly independent thermostable grid may still be required to serve as a critical anchor to secure the stereospecific thermoactivity. Its end melting temperature thresholds, together with the start ones of the biggest grids in the evolved variants, may confer high temperature sensitivity against thermal inactivation. Collectively, this computational study may have widespread significance in advancing our complete understanding and biotechnology of the thermoadaptive mechanism of the structural thermostability of a biological macromolecule.

Hysteretic electronic phase transitions in correlated charge density wave state of 1T−TaS2

The layered transition metal dichalcogenide $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ has evoked great interest owing to its particularly rich electronic phase diagram including different charge density wave (CDW) phases. However, few studies have focused on its hysteretic electronic phase transitions based on the in-depth discussion of the delicate interplay among temperature-dependent electronic interactions. Here, we report a sequence of spatial electronic phase transitions in the hysteresis temperature range (160--230 K) of $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ via variable-temperature scanning tunneling microscopy. Several emergent electronic states are investigated at multiscale during the commensurate CDW--triclinic CDW (CCDW-TCDW) phase transitions: a spotty-CDW state above $\ensuremath{\sim}160\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a network-CDW (NCDW) state above $\ensuremath{\sim}180\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ during the warmup process, a belt-TCDW state below $\ensuremath{\sim}230\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a NCDW state below $\ensuremath{\sim}200\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, and finally a mosaic-CDW state below $\ensuremath{\sim}160\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ during cooldown from the TCDW phase. These emergent electronic states are associated with the delicate temperature-dependent competition and/or cooperation of stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon ($e\text{\ensuremath{-}}ph$) coupling of $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$. Our results not only provide insight to understand the hysteretic electronic phase transitions in the correlated CDW state, but also pave a way to realize more exotic quantum states by accurately and effectively tuning various interior interactions in correlated materials.

Thermal first-order phase transitions, Ising critical points, and reentrance in the Ising-Heisenberg model on the diamond-decorated square lattice in a magnetic field

The thermal phase transitions of a spin-1/2 Ising-Heisenberg model on the diamond-decorated square lattice in a magnetic field are investigated using a decoration-iteration transformation and classical Monte Carlo simulations. A generalized decoration-iteration transformation maps this model exactly onto an effective classical Ising model on the square lattice with temperature-dependent effective nearest-neighbor interactions and magnetic field strength. The effective field vanishes along a ground-state phase boundary of the original model, separating a ferrimagnetic and a quantum monomer-dimer phase. At finite temperatures this phase boundary gives rise to an exactly solvable surface of discontinuous (first-order) phase transitions, which terminates in a line of Ising critical points. The existence of discontinuous reentrant phase transitions within a narrow parameter regime is reported and explained in terms of the low-energy excitations from both phases. These exact results, obtained from the mapping to the zero-field effective Ising model are corroborated by classical Monte Carlo simulations of the effective model.

The Network Basis for the Structural Thermostability and the Functional Thermoactivity of Aldolase B

Thermostability is important for the thermoactivity of proteins including enzymes. However, it is still challenging to pinpoint the specific structural factors for different temperature thresholds to initiate their specific structural and functional perturbations. Here, graph theory was used to investigate how the temperature-dependent noncovalent interactions as identified in the structures of aldolase B and its prevalent A149P mutant could form a systematic fluidic grid-like mesh network with topological grids to regulate the structural thermostability and the functional thermoactivity upon cyclization against decyclization in an extended range of a subunit. The results showed that the biggest grid may determine the melting temperature thresholds for the changes in their secondary and tertiary structures and specific catalytic activities. Further, a highly conserved thermostable grid may serve as an anchor to secure the flexible active site to achieve the specific thermoactivity. Finally, higher grid-based systematic thermal instability may disfavor the thermoactivity. Thus, this computational study may provide critical clues for the structural thermostability and the functional thermoactivity of proteins including enzymes.

Concentration and temperature dependent interactions and state diagram of dispersions of copolymer microgels.

We investigate by means of small angle neutron scattering experiments and numerical simulations the interactions and inter-particle arrangements of concentrated dispersions of copolymer poly(N-isopropylacrylamide)-poly(ethylene glycol methyl ether methacrylate) (PNIPAM-PEGMA) microgels across the volume phase transition (VPT). The scattering data of moderately concentrated dispersions are accurately modeled at all temperatures by using a star polymer form factor and static structure factors calculated from the effective potential obtained from simulations. Interestingly, for temperatures below the VPT temperature (VPTT), the radius of gyration and blob size of the particles significantly decrease with increasing the effective packing fraction in the non-overlapping regime. This is attributed to the presence of charges in the system associated with the use of an ionic initiator in the synthesis. Simulations using the experimentally corroborated interaction potential are used to explore the state diagram in a wide range of effective packing fractions. Below and slightly above the VPTT, the system undergoes an arrest transition mainly driven by the soft repulsion between the particles. Only well above the VPTT the system is found to phase separate before arresting. Our results highlight the versatility and potential of copolymer PNIPAM-PEGMA microgels to explore different kinds of arrested states balancing attraction and repulsion by changing temperature and packing fraction.

The Common Bean Small Heat Shock Protein Nodulin 22 from Phaseolus vulgaris L. Assembles into Functional High-Molecular-Weight Oligomers.

Small heat shock proteins (sHsps) are present in all domains of life. These proteins are responsible for binding unfolded proteins to prevent their aggregation. sHsps form dynamic oligomers of different sizes and constitute transient reservoirs for folding competent proteins that are subsequently refolded by ATP-dependent chaperone systems. In plants, the sHsp family is rather diverse and has been associated with the ability of plants to survive diverse environmental stresses. Nodulin 22 (PvNod22) is an sHsp of the common bean (Phaseolus vulgaris L.) located in the endoplasmic reticulum. This protein is expressed in response to stress (heat or oxidative) or in plant roots during mycorrhizal and rhizobial symbiosis. In this work, we study its oligomeric state using a combination of in silico and experimental approaches. We found that recombinant PvNod22 was able to protect a target protein from heat unfolding in vitro. We also demonstrated that PvNod22 assembles into high-molecular-weight oligomers with diameters of ~15 nm under stress-free conditions. These oligomers can cluster together to form high-weight polydisperse agglomerates with temperature-dependent interactions; in contrast, the oligomers are stable regarding temperature.

Magnetism and Raman Investigations of Hydrothermally Reduced Graphene Oxide-Incorporated α-Fe2O3 Nanocomposites: The Role of Temperature-Dependent Charge Transfer-Induced Interfacial Interactions

Magnetism and Raman Investigations of Hydrothermally Reduced Graphene Oxide-Incorporated α-Fe₂O₃ Nanocomposites: The Role of Temperature-Dependent Charge Transfer-Induced Interfacial Interactions

FLOWERING LOCUS M isoforms differentially affect the subcellular localization and stability of SHORT VEGETATIVE PHASE to regulate temperature-responsive flowering in Arabidopsis

Temperature is an important environmental cue that affects flowering time in plants. The MADS-box transcription factor FLOWERING LOCUS M (FLM) forms a heterodimeric complex with SHORT VEGETATIVE PHASE (SVP) and controls ambient temperature-responsive flowering in Arabidopsis. FLM-β and FLM-δ, two major splice variants produced from the FLM locus, exert opposite effects on flowering, but the molecular mechanism by which the interaction between FLM isoforms and SVP affects temperature-responsive flowering remains poorly understood. Here, we show that FLM-β and FLM-δ play important roles in modulating the temperature-dependent behavior, conformation, and stability of SVP. Nuclear localization of SVP decreases as temperature increases. FLM-β is required for SVP nuclear translocation at low temperature, whereas SVP interacts with FLM-δ mainly in the cytoplasm at high temperature. SVP preferentially binds to FLM-β at low temperature in tobacco leaf cells. SVP shows high binding affinity to FLM-β at low temperature and to FLM-δ at high temperature. SVP undergoes similar structural changes in the interactions with FLM-β and FLM-δ; however, FLM-δ likely causes more pronounced conformational changes in the SVP structure. FLM-δ causes rapid degradation of SVP at high temperature, compared with FLM-β, possibly via ubiquitination. Mutation of lysine 53 or lysine 165 in SVP causes increased abundance of SVP due to reduced ubiquitination of SVP and thus delays flowering at high temperature. Our findings suggest that temperature-dependent differential interactions between SVP and FLM isoforms modulate the temperature-responsive induction of flowering in Arabidopsis.

A long-range order in a thermally driven system with temperature-dependent interactions.

Aggregation of macro-molecules under an external force is far from being understood. An important driving situation is achieved by temperature difference. Inter-particle interactions in metallic nanoparticles with ligand capping are reported to be sensitive to temperature and the zeta potential of the particles being reduced in the cold region. Such particles form aggregates in the cold region of the system in the presence of temperature difference. Here we study the aggregation of particles in the presence of temperature difference with temperature-dependent interaction parameters using Brownian dynamics simulation. The particle interaction and particle diffusion are considered to be sensitive to the local temperature. We identify a long-range structural order in the cold region of the system using the Avrami equation for crystal growth kinetics. Our observations might be useful in designing ordered structures with macro-molecules under non-equilibrium steady-state conditions.