Integrated development of low-temperature thermal waters

The research concerns the efficient development of low-potential thermal waters in the East-Ciscaucasian artesian basin. A technology is proposed for the integrated development of low-temperature thermal water, using its heat potential for district heating and hot water supply, as well the water itself for various water management purposes, with its quality previously brought to the standards of drinking water. Various chemical water treatment units are suggested for this purpose, with their design and technological features being formed depending on the quality of the source water. The system will enable the maximization of the resource potential of the geothermal well and its all-year-round operation. The paper shows the efficiency of using the potential of geothermal energy resources in energy- biological complexes. The geothermal-biogas technology with the integrated application of thermal waters for various needs is presented. Such thermal water utilization provides for the most efficient use of its thermal potential with a decrease in temperature to a value close to the ambient temperature.

Systematic assessment of the accuracy of subunit counting in biomolecular complexes using automated single molecule brightness analysis

Analysis of single molecule brightness allows subunit counting of high-order oligomeric biomolecular complexes. Although the theory behind the method has been extensively assessed, systematic analysis of the experimental conditions required to accurately quantify the stoichiometry of biological complexes remains challenging. In this work, we develop a high-throughput, automated computational pipeline for single molecule brightness analysis that requires minimal human input. We use this strategy to systematically quantify the accuracy of counting under a wide range of experimental conditions in simulated ground-truth data and then validate its use on experimentally obtained data. Our approach defines a set of conditions under which subunit counting by brightness analysis is designed to work optimally and helps establishing the experimental limits in quantifying the number of subunits in a complex of interest. Finally, we combine these features into a powerful, yet simple, software that can be easily used for the stoichiometry analysis of such complexes.

Spin Labeling of Surface Cysteines Using a Bromoacrylaldehyde Spin Label

Structural investigations of proteins and their biological complexes are now frequently complemented by distance constraints between spin labeled cysteines generated using double electron–electron resonance (DEER) spectroscopy, via site directed spin labeling (SDSL). Methanethiosulfonate spin label (MTSSL), has become ubiquitous in the SDSL of proteins, however, has limitations owing to its high number of rotamers, and reducibility. In this article we introduce the use of bromoacrylaldehyde spin label (BASL) as a cysteine spin label, demonstrating an advantage over MTSSL due to its increased selectivity for surface cysteines, eliminating the need to ‘knock out’ superfluous cysteine residues. Applied to the multidomain protein, His domain protein tyrosine phosphatase (HD-PTP), we show that BASL can be easily added in excess with selective labeling, whereas MTSSL causes protein precipitation. Furthermore, using DEER, we were able to measure a single cysteine pair distance in a three cysteine domain within HD-PTP. The label has a further advantage of comprising a sulfide in a three-bond tether, making it a candidate for protein binding and in-cell studies.

Heliorhodopsin evolution is driven by photosensory promiscuity in monoderms

The ability to harness Sun’s electromagnetic radiation by channeling it into high-energy phosphate bonds empowered microorganisms to tap into a cheap and inexhaustible source of energy. Life’s billion-years history of metabolic innovations led to the emergence of only two biological complexes capable of harvesting light: one based on rhodopsins and the other on (bacterio)chlorophyll. Rhodopsins encompass the most diverse and abundant photoactive proteins on Earth and were until recently canonically split between type-1 (microbial rhodopsins) and type-2 (animal rhodopsins) families. Unexpectedly, the long-lived type-1/type-2 dichotomy was recently amended through the discovery of heliorhodopsins (HeRs) (Pushkarev et al. 2018), a novel and exotic family of rhodopsins (i.e. type-3) that evaded recognition in our current homology-driven scrutiny of life’s genomic milieu. Here, we bring to resolution the debated monoderm/diderm occurrence patterns by conclusively showing that HeR distribution is restricted to monoderms. Furthermore, through investigating protein domain fusions, contextual genomic information, and gene co-expression data we show that HeRs likely function as generalised light-dependent switches involved in the mitigation of light-induced oxidative stress and metabolic circuitry regulation. We reason that HeR’s ability to function as sensory rhodopsins is corroborated by their photocycle dynamics (Pushkarev et al. 2018) and that their presence and function in monoderms is likely connected to the increased sensitivity to light-induced damage of these organisms (Maclean et al. 2009).

Dual-Channel Stopped-Flow Apparatus for Simultaneous Fluorescence, Anisotropy, and FRET Kinetic Data Acquisition for Binary and Ternary Biological Complexes

The Stopped-Flow apparatus (SF) tracks molecular events by mixing the reactants in sub-millisecond regimes. The reaction of intrinsically or extrinsically labeled biomolecules can be monitored by recording the fluorescence, F(t), anisotropy, r(t), polarization, p(t), or FRET, F(t)FRET, traces at nanomolar concentrations. These kinetic measurements are critical to elucidate reaction mechanisms, structural information, and even thermodynamics. In a single detector SF, or L-configuration, the r(t), p(t), and F(t) traces are acquired by switching the orientation of the emission polarizer to collect the IVV and IVH signals however it requires two-shot experiments. In a two-detector SF, or T-configuration, these traces are collected in a single-shot experiment, but it increases the apparatus’ complexity and price. Herein, we present a single-detector dual-channel SF to obtain the F(t) and r(t) traces simultaneously, in which a photo-elastic modulator oscillates by 90° the excitation light plane at a 50 kHz frequency, and the emission signal is processed by a set of electronic filters that split it into the r(t) and F(t) analog signals that are digitized and stored into separated spreadsheets by a custom-tailored instrument control software. We evaluated the association kinetics of binary and ternary biological complexes acquired with our dual-channel SF and the traditional methods; such as a single polarizer at the magic angle to acquire F(t), a set of polarizers to track F(t), and r(t), and by energy transfer quenching, F(t)FRET. Our dual-channel SF economized labeled material and yielded rate constants in excellent agreement with the traditional methods.

The Human Proteoform Project: A Plan to Define the Human Proteome

Proteins are the primary effectors of function in biology, and thus complete knowledge of their structure and properties is fundamental to deciphering function in basic and translational research. The chemical diversity of proteins is expressed in their many proteoforms, which result from combinations of genetic polymorphisms, RNA splice variants and post-translational modifications. This knowledge is foundational for the biological complexes and networks that control biology, yet remains largely unknown. We propose here an ambitious initiative to define the human proteome; that is to generate a definitive reference set of the proteoforms produced from the genome. Several examples of the power and importance of proteoform-level knowledge in disease-based research are presented, along with a call for improved technologies in a two-pronged strategy to accomplish the Human Proteoform Project.

Climbing up and down binding landscapes: a high-throughput study of mutational effects in homologous protein-protein complexes

Each protein-protein interaction (PPI) has evolved to possess binding affinity that is compatible with its cellular function. As such, cognate enzyme/inhibitor interactions frequently exhibit very high binding affinities, while structurally similar non-cognate PPIs possess substantially weaker binding affinities. To understand how slight differences in sequence and structure could lead to drastic changes in PPI binding free energy (ΔΔGbind), we study three homologous PPIs that span nine orders of magnitude in binding affinity and involve a serine protease interacting with an inhibitor BPTI. Using state-of-the-art methodology that combines protein randomization and affinity sorting coupled to next-generation sequencing and data normalization, we report quantitative binding landscapes consisting of ΔΔGbind values for the three PPIs, gleaned from tens of thousands of single and double mutations in the BPTI binding interface. We demonstrate that the three homologous PPIs possess drastically different binding landscapes and lie at different points in respect to the landscape maximum. Furthermore, the three PPIs demonstrate distinct patterns of coupling energies between two simultaneous mutations that depend not only on positions involved but also on the nature of the mutation. Interestingly, we find that in all three PPIs positive epistasis is frequently observed at hot-spot positions where mutations lead to loss of high affinity, while conversely negative epistasis is observed at cold-spot positions, where mutations lead to affinity enhancement. The new insights on PPI evolution revealed in this study will be invaluable in understanding evolution of other biological complexes and can greatly facilitate design of novel high-affinity protein inhibitors.SignificanceProtein-protein interactions (PPIs) have evolved to display binding affinities that can support their function. As such, cognate and non-cognate PPIs could be highly similar structurally but exhibit huge differences in binding affinities. To understand this phenomenon, we studied the effect of tens of thousands of single and double mutations on binding affinity of three homologous protease-inhibitor complexes. We show that binding landscapes of the three complexes are strikingly different and depend on the PPI evolutionary optimality. We observe different patterns of couplings between mutations for the three PPIs with negative and positive epistasis appearing most frequently at hot-spot and cold-spot positions, respectively. The evolutionary trends observed here are likely to be universal to all biological complexes in the cell.

Dynamic behavior of biomaterials uncovered by cryo-electron microscopy.

: Structural biology develops rapidly as time goes on. Based only on static structure analysis of biomaterials is not enough to satisfy the studies of their functional mechanisms, with a huge obstacle for the dynamic process of biological complexes. The rapid development of cryo-electron microscopy(cryo-EM) technology makes that it is possible to observe the near-atomic resolution structures and dynamic nature of biological macromolecules, in the fields of dynamic characteristics of proteins, protein-protein interactions, molecular recognition, and structure-based design. In this review, we systematically elaborate the contribution of cryo-EM technology in the field of biomaterials such as ribosome motion, membrane protein structure and conformational space, dynamic transmission within the plasma membrane and clinical applications. We also put forwards a new standpoint in the development of cryo-EM technology.