Project description:We developed a robust method termed Dali that identifies phosphorylation events that alter protein thermal stability as a proxy for function.
Project description:Thermal proteome profiling (TPP) has significantly advanced the field of drug discovery by facilitating proteome-wide identification of drug targets and off-targets. However, TPP has not been widely applied for high-throughput drug screenings, since the method is labor intensive and requires a lot of measurement time on a mass spectrometer. Here, we present Single-tube TPP with Uniform Progression (STPP-UP), which significantly reduces both the amount of required input material and measurement time, while retaining the ability to identify drug targets for compounds of interest. By using incremental heating of a single sample, changes in protein thermal stability across a range of temperatures can be assessed, while alleviating the need to measure multiple samples heated to different temperatures. We demonstrate that STPP-UP is able to identify the direct interactors for anticancer drugs in both human and mice cells. In summary, the STPP-UP methodology represents a useful tool to advance drug discovery and drug repurposing efforts.
Project description:The stability of protein folded states is crucial for its function, yet the relationship with the protein sequence remains poorly understood. Prior studies have focused on the amino acid composition and thermodynamic couplings within a single folded conformation, overlooking the potential contribution of protein dynamics. Here, we address this gap by systematically analyzing the impact of alanine mutations in the C-terminal β-strand (β5) of ubiquitin, a model protein exhibiting millisecond timescale interconversion between two conformational states differing in the β5 position. Our findings unveil a negative correlation between millisecond dynamics and thermal stability, with alanine substitutions at seemingly flexible C-terminal residues significantly enhancing thermostability. Integrating spectroscopic and computational approaches, we demonstrate that the thermally unfolded state retains a substantial secondary structure but lacks β5 engagement, recapitulating the transition state for millisecond dynamics. Thus, alanine mutations that modulate the stabilities of the folded states with respect to the partially unfolded state impact both the dynamics and stability. Our findings underscore the importance of conformational dynamics with implications for protein engineering and design.
Project description:Thermal stability shift analysis is a powerful method for examining binding interactions in proteins. We demonstrate that under certain circumstances, protein-protein interactions can be quantitated by monitoring shifts in thermal stability using thermodynamic models and data analysis methods presented in this work. This method relies on the determination of protein stabilities from thermal unfolding experiments using fluorescent dyes such as SYPRO Orange that report on protein denaturation. Data collection is rapid and straightforward using readily available real-time polymerase chain reaction instrumentation. We present an approach for the analysis of the unfolding transitions corresponding to each partner to extract the affinity of the interaction between the proteins. This method does not require the construction of a titration series that brackets the dissociation constant. In thermal shift experiments, protein stability data are obtained at different temperatures according to the affinity- and concentration-dependent shifts in unfolding transition midpoints. Treatment of the temperature dependence of affinity is, therefore, intrinsic to this method and is developed in this study. We used the interaction between maltose-binding protein (MBP) and a thermostable synthetic ankyrin repeat protein (Off7) as an experimental test case because their unfolding transitions overlap minimally. We found that MBP is significantly stabilized by Off7. High experimental throughput is enabled by sample parallelization, and the ability to extract quantitative binding information at a single partner concentration. In a single experiment, we were able to quantify the affinities of a series of alanine mutants, covering a wide range of affinities (∼ 100 nM to ∼ 100 μM).
Project description:Protein methylation is an important modification beyond epigenetics. However, systems analyses of protein methylation lag behind compared to other modifications. Recently, thermal stability analyses have been developed which provide a proxy of a protein functional status. Here, we show that molecular and functional events closely linked to protein methylation can be revealed by the analysis of thermal stability. Using mouse embryonic stem cells as a model, we show that Prmt5 regulates mRNA binding proteins that are enriched in intrinsically disordered regions and involved in liquid-liquid phase separation mechanisms, including the formation of stress granules. Moreover, we reveal a non-canonical function of Ezh2 in mitotic chromosomes and the perichromosomal layer, and identify Mki67 as a putative Ezh2 substrate. Our approach provides an opportunity to systematically explore protein methylation function and represents a rich resource for understanding its role in pluripotency.
Project description:MotivationThermal properties of proteins are of great importance for a number of theoretical and practical implications. Predicting the thermal stability of a protein is a difficult and still scarcely addressed task.ResultsHere, we introduce Thermometer, a webserver to assess the thermal stability of a protein using structural information. Thermometer is implemented as a publicly available, user-friendly interface.Availability and implementationOur server can be found at the following link (all major browser supported): http://service.tartaglialab.com/new_submission/thermometer_file.Supplementary informationSupplementary data are available at Bioinformatics online.
Project description:Quantitative mass spectrometry has established proteome-wide regulation of protein abundance and post-translational modifications in various biological processes. Here, we used quantitative mass spectrometry to systematically analyze the thermal stability and solubility of proteins on a proteome-wide scale during the eukaryotic cell cycle. We demonstrate pervasive variation of these biophysical parameters with most changes occurring in mitosis and G1. Various cellular pathways and components vary in thermal stability, such as cell-cycle factors, polymerases, and chromatin remodelers. We demonstrate that protein thermal stability serves as a proxy for enzyme activity, DNA binding, and complex formation in situ. Strikingly, a large cohort of intrinsically disordered and mitotically phosphorylated proteins is stabilized and solubilized in mitosis, suggesting a fundamental remodeling of the biophysical environment of the mitotic cell. Our data represent a rich resource for cell, structural, and systems biologists interested in proteome regulation during biological transitions.
Project description:The data presented here are related to the research article entitled "Expression, purification, and preliminary characterization of human presenilin-2" [1]. Human Presenilin-2 is the catalytic subunit of ?-secretase and a possible calcium leakage channel (Kimberly et al., 2000; Tu et al., 2006) [2], [3]. HisPS2 which was obtained by overexpression in E. coli strain C43 (DE3) was extracted by detergent solubilisation. The sample isolation efficiency by detergents and the protein identification by mass spectrometry and western blot are described. This data article describes the near and far UV circular dichroism measurements and the data deconvolution in terms of secondary structure at 4 and 98?°C. Also, a refolding spectrum is presented. The raw CD spectra used for deconvolution of the helix and stand segments and average length are deposited into Protein Circular Dichroism Data Bank with PCDDBid: CD0005962000 (4?°C far UV), CD0005963000 (98?°C far UV), CD0005964000 (back to 4?°C far UV) and CD0005965000 (4?°C near UV CD).
Project description:We present the software CDpal that is used to analyze thermal and chemical denaturation data to obtain information on protein stability. The software uses standard assumptions and equations applied to two-state and various types of three-state denaturation models in order to determine thermodynamic parameters. It can analyze denaturation monitored by both circular dichroism and fluorescence spectroscopy and is extremely flexible in terms of input format. Furthermore, it is intuitive and easy to use because of the graphical user interface and extensive documentation. As illustrated by the examples herein, CDpal should be a valuable tool for analysis of protein stability.
Project description:DZNep (3-deazaneplanocin A) is commonly used to reduce lysine methylation. DZNep inhibits S-adenosyl-L-homocysteine hydrolase (AHCY), preventing the conversion of S-adenosyl-L-homocysteine (SAH) into L-homocysteine and reducing the level of S-adenosylmethionine (SAM). As a result, the SAM to SAH ratio decreases, an indicator of the methylation potential within a cell. Many studies have characterized the impact of DZNep on histone lysine methylation or in specific cell or disease contexts. Recently, protein thermal stability has provided a new dimension for studying the mechanism of action of small molecule inhibitors. In addition to ligand binding, post-translational modifications and protein-protein interactions impact thermal stability. Here, we sought to characterize protein thermal stability changes induced by DZNep treatment in HEK293T cells using the Protein Integral Solubility Alteration (PISA) assay. DZNep treatment altered the thermal stability of 135 proteins, with over half previously reported to be methylated at lysine residues. In addition to thermal stability, we identify changes in transcript and protein abundance after DZNep treatment to distinguish between direct and indirect impacts on thermal stability. Nearly one-third of the proteins with altered thermal stability had no changes at the transcript or protein level. Of these thermally altered proteins, CDK6 had a stabilized methylated peptide, while its unmethylated counterpart was unaltered. Multiple methyltransferases were among the proteins with thermal stability alteration, including DNMT1, potentially due to changes in SAM/SAH levels. This study systematically evaluates DZNep’s impact on the transcriptome, the proteome, and the thermal stability of proteins.