Solvent-Induced Lag Phase during the Formation of Lysozyme Amyloid Fibrils Triggered by Sodium Dodecyl Sulfate: Biophysical Experimental and In Silico Study of Solvent Effects.

Amyloid aggregates arise from either the partial or complete loss of the native protein structure or the inability of proteins to attain their native conformation. These aggregates have been linked to several diseases, including Alzheimer's, Parkinson's, and lysozyme amyloidosis. A comprehensive dataset was recently reported, demonstrating the critical role of the protein's surrounding environment in amyloid formation. In this study, we investigated the formation of lysozyme amyloid fibrils induced by sodium dodecyl sulfate (SDS) and the effect of solvents in the medium. Experimental data obtained through fluorescence spectroscopy revealed a notable lag phase in amyloid formation when acetone solution was present. This finding suggested that the presence of acetone in the reaction medium created an unfavorable microenvironment for amyloid fibril formation and impeded the organization of the denatured protein into the fibril form. The in silico data provided insights into the molecular mechanism of the interaction between acetone molecules and the lysozyme protofibril, once acetone presented the best experimental results. It was observed that the lysozyme protofibril became highly unstable in the presence of acetone, leading to the complete loss of its ß-sheet conformation and resulting in an open structure. Furthermore, the solvation layer of the protofibril in acetone solution was significantly reduced compared to that in other solvents, resulting in fewer hydrogen bonds. Consequently, the presence of acetone facilitated the exposure of the hydrophobic portion of the protofibril, precluding the amyloid fibril formation. In summary, our study underscores the pivotal role the surrounding environment plays in influencing amyloid formation.

Suspected adverse drug reactions of the type 2 antidiabetic drug class dipeptidyl-peptidase IV inhibitors (DPP4i): Can polypharmacology help explain?

To interpret the relationship between the polypharmacology of dipeptidyl-peptidase IV inhibitors (DPP4i) and their suspected adverse drug reaction (ADR) profiles using a national registry. A retrospective investigation into the suspected ADR profile of four licensed DPP4i in the United Kingdom using the National MHRA Yellow Card Scheme and OpenPrescribing databases. Experimental data from the ChEMBL database alongside physiochemical (PC) and pharmacokinetic (PK) profiles were extracted and interpreted. DPP4i show limited polypharmacology alongside low suspected ADR rates. We found a minimal statistical difference between the unique ADR profiles ascribed to the DPP4i except for total ADRs (χ2 ; p < .05). Alogliptin consistently showed the highest suspected ADR rate per 1 000 000 items prescribed. Saxagliptin showed the lowest suspected ADR rate across all organ classes but did not reach statistical difference (χ2 ; p > .05). We confirmed the Phase III clinical trial data that showed gastrointestinal and skin reactions are the most reported ADRs across the DPP4i class and postulated underlying mechanisms for this based on possible drug interactions. The main pharmacological mechanism behind the ADRs is attributed to interactions with DPP4 activity and/or structure homolog (DASH) proteins which augment the immune-inflammatory modulation of DPP4.

A Computational-Experimental Investigation of the Molecular Mechanism of Interleukin-6-Piperine Interaction.

Herein, we elucidate the biophysical aspects of the interaction of an important protein, Interleukin-6 (IL6), which is involved in cytokine storm syndrome, with a natural product with anti-inflammatory activity, piperine. Despite the role of piperine in the inhibition of the transcriptional protein NF-κB pathway responsible for activation of IL6 gene expression, there are no studies to the best of our knowledge regarding the characterisation of the molecular interaction of the IL6-piperine complex. In this context, the characterisation was performed with spectroscopic experiments aided by molecular modelling. Fluorescence spectroscopy alongside van't Hoff analyses showed that the complexation event is a spontaneous process driven by non-specific interactions. Circular dichroism aided by molecular dynamics revealed that piperine caused local α-helix reduction. Molecular docking and molecular dynamics disclosed the microenvironment of interaction as non-polar amino acid residues. Although piperine has three available hydrogen bond acceptors, only one hydrogen-bond was formed during our simulation experiments, reinforcing the major role of non-specific interactions that we observed experimentally. Root mean square deviation (RMSD) and hydrodynamic radii revealed that the IL6-piperine complex was stable during 800 ns of simulation. Taken together, these results can support ongoing IL6 drug discovery efforts.

Angiotensin II receptor blockers (ARBs) and manufacturing contamination: A retrospective National Register Study into suspected associated adverse drug reactions.

AIMS: The aim of this study was to determine if any suspected adverse drug reactions (ADRs) observed with the use of angiotensin II receptor blockers (ARBs) could be linked to either (a) their unique respective physicochemical and pharmacological profiles and (b) the recently disclosed suspected carcinogenic manufacturing contaminants found in certain sartan drug class batches. METHODS: The pharmacology profiles of ARBs were data-mined from the Chemical Database of bioactive molecules with drug-like properties, European Molecular Biology Laboratory (ChEMBL). Suspected ADR data (from 01/2016-10/2022, inclusive) and prescribing rates of ARBs over a 5-year prescribing window (from 09/2016 to 08/2021, inclusive) were obtained via analysis of the United Kingdom Medicines and Healthcare products Regulatory Authority (MHRA) Yellow Card drug analysis profile and Open prescribing databases, respectively. RESULTS: The overall suspected ADRs and fatalities per 100 000 prescriptions identified across the ARBs studied were found to be different between the sartan drug class members (chi-squared test, P < .05). There is a greater relative rate of reports for valsartan across all investigated organ classes of ADRs, than other ARBs, despite valsartan's more limited pharmacological profile and similar physicochemical properties to other sartans. The disparity in ADR reporting rates with valsartan vs other ARBs could be due to the dissimilarity in formulation excipients, patient factors and publicity surrounding batch contaminations, amongst others. Cancer-related ADRs and fatalities per 100 000 prescriptions identified across the ARBs studied are not statistically significant (chi-squared test, P > .05) based on the datasets used over the 5-year period. CONCLUSION: No connection between ARB pharmacology and their suspected ADRs could be found. No conclusion between sartan batch contaminations and increased suspected cancer-related ADRs was found.

Discovery and Characterization of a Cryptic Secondary Binding Site in the Molecular Chaperone HSP70.

Heat Shock Protein 70s (HSP70s) are key molecular chaperones that are overexpressed in many cancers and often associated with metastasis and poor prognosis. It has proven difficult to develop ATP-competitive, drug-like small molecule inhibitors of HSP70s due to the flexible and hydrophilic nature of the HSP70 ATP-binding site and its high affinity for endogenous nucleotides. The aim of this study was to explore the potential for the inhibition of HSP70 through alternative binding sites using fragment-based approaches. A surface plasmon resonance (SPR) fragment screen designed to detect secondary binding sites in HSP70 led to the identification by X-ray crystallography of a cryptic binding site in the nucleotide-binding domain (NBD) of HSP70 adjacent to the ATP-binding site. Fragment binding was confirmed and characterized as ATP-competitive using SPR and ligand-observed NMR methods. Molecular dynamics simulations were applied to understand the interactions with the protein upon ligand binding, and local secondary structure changes consistent with interconversion between the observed crystal structures with and without the cryptic pocket were detected. A virtual high-throughput screen (vHTS) against the cryptic pocket was conducted, and five compounds with diverse chemical scaffolds were confirmed to bind to HSP70 with micromolar affinity by SPR. These results identified and characterized a new targetable site on HSP70. While targeting HSP70 remains challenging, the new site may provide opportunities to develop allosteric ATP-competitive inhibitors with differentiated physicochemical properties from current series.

Identification of different side effects between PARP inhibitors and their polypharmacological multi-target rationale.

AIMS: The aim of this study was to determine the differences and potential mechanistic rationale for observed adverse drug reactions (ADRs) between four approved PARP inhibitors (PARPi). METHODS: The Medicines and Healthcare products Regulatory Authority (MHRA) Yellow Card drug analysis profiles and NHS secondary care medicines database enabled the identification of suspected ADRs associated with the PARPi in the UK from launch to 2020. The polypharmacology of the PARPi were data-mined from several public data sources. RESULTS: The overall ADRs per 100 000 Rx identified across the four PARPi are statistically significant (χ2 test, P < .001). Rucaparib has the greatest relative suspected ADRs, which can be explained by its least clean kinome and physicochemical properties. The suspected gastrointestinal ADRs of rucaparib and niraparib can be ascribed to their kinase polypharmacology. Suspected blood and lymphatic system ADRs of PARPi can be linked to their high volume of distribution (Vd ). The thrombocytopenia rate of niraparib > rucaparib > olaparib tracked with the Vd trend. Hypertension is only associated with niraparib and could be explained by the therapeutically achievable inhibition of DYRK1A and/or transporters. Arrhythmia cases are potentially linked to the structural features of hERG ion-channel inhibition found in rucaparib and niraparib. Enhanced psychiatric/nervous disorders associated with niraparib can be interpreted from the diverse neurotransporter off-targets reported. CONCLUSIONS: Despite their similar mode of action, the differential polypharmacology of PARP inhibitors influences their ADR profile.

Unravelling the Interaction of Piperlongumine with the Nucleotide-Binding Domain of HSP70: A Spectroscopic and In Silico Study.

Piperlongumine (PPL) is an alkaloid extracted from several pepper species that exhibits anti-inflammatory and anti-carcinogenic properties. Nevertheless, the molecular mode of action of PPL that confers such powerful pharmacological properties remains unknown. From this perspective, spectroscopic methods aided by computational modeling were employed to characterize the interaction between PPL and nucleotide-binding domain of heat shock protein 70 (NBD/HSP70), which is involved in the pathogenesis of several diseases. Steady-state fluorescence spectroscopy along with time-resolved fluorescence revealed the complex formation based on a static quenching mechanism. Van't Hoff analyses showed that the binding of PPL toward NBD is driven by equivalent contributions of entropic and enthalpic factors. Furthermore, IDF and Scatchard methods applied to fluorescence intensities determined two cooperative binding sites with Kb of (6.3 ± 0.2) × 104 M-1. Circular dichroism determined the thermal stability of the NBD domain and showed that PPL caused minor changes in the protein secondary structure. Computational simulations elucidated the microenvironment of these interactions, showing that the binding sites are composed mainly of polar amino acids and the predominant interaction of PPL with NBD is Van der Waals in nature.

Polypharmacology of clinical sodium glucose co-transport protein 2 inhibitors and relationship to suspected adverse drug reactions.

Sodium glucose co-transporter 2 inhibitors (SGLT2i) are a promising second-line treatment strategy for type 2 diabetes mellitus (T2DM) with a developing landscape of both beneficial cardio- and nephroprotective properties and emerging adverse drug reactions (ADRs) including diabetic ketoacidosis (DKA), genetic mycotic infections, and amputations among others. A national register study (MHRA Yellow Card, UK) was used to quantify the SGLT2i's suspected ADRs relative to their Rx rate (OpenPrescribing, UK). The polypharmacology profiles of SGLT2i were data-mined (ChEMBL) for the first time. The ADR reports (n = 3629) and prescribing numbers (Rx n = 5,813,325) for each SGLT2i in the United Kingdom (from launch date to the beginning December 2019) were determined. Empagliflozin possesses the most selective SGLT2/SGLT1 inhibition profile at ~2500-fold, ~10-fold more selective than cangliflozin (~260-fold). Canagliflozin was found to also inhibit CYP at clinically achievable concentrations. We find that for overall ADR rates, empagliflozin versus dapagliflozin and empagliflozin versus canagliflozin are statistically significant (χ2 , p < .05), while dapagliflozin versus canagliflozin is not. In terms of overall ADRs, there is a greater relative rate for canagliflozin > dapagliflozin > empagliflozin. For fatalities, there is a greater relative rate for dapagliflozin > canagliflozin > empagliflozin. An organ classification that resulted in a statistically significant difference between SGLT2i was suspected infection/infestation ADRs between empagliflozin and dapagliflozin. Our findings at this stage of SGLT2i usage in the United Kingdom suggest that empagliflozin, the most selective SGLT2i, had the lowest suspected ADR incident rate (relative to prescribing) and in all reported classes of ADRs identified including infections, amputations, and DKA.

Organoruthenium Complexes with Benzo-Fused Pyrithiones Overcome Platinum Resistance in Ovarian Cancer Cells.

Drug resistance to existing anticancer agents is a growing clinical concern, with many first line treatments showing poor efficacy in treatment plans of some cancers. Resistance to platinum agents, such as cisplatin, is particularly prevalent in the treatment of ovarian cancer, one of the most common cancers amongst women in the developing world. Therefore, there is an urgent need to develop next generation of anticancer agents which can overcome resistance to existing therapies. We report a new series of organoruthenium(II) complexes bearing structurally modified pyrithione ligands with extended aromatic scaffold, which overcome platinum and adriamycin resistance in human ovarian cancer cells. The mechanism of action of such complexes appears to be unique from that of cisplatin, involving G1 cell cycle arrest without generation of cellular ROS, as is typically associated with similar ruthenium complexes. The complexes inhibit the enzyme thioredoxin reductase (TrxR) in a model system and reduce cell motility towards wound healing. Importantly, this work highlights further development in our understanding of the multi-targeting mechanism of action exhibited by transition metal complexes.

Aminothiazolones as potent, selective and cell active inhibitors of the PIM kinase family.

We have previously reported the discovery of a series of rhodanine-based inhibitors of the PIM family of serine/threonine kinases. Here we described the optimisation of those compounds to improve their physicochemical and ADME properties as well as reducing their off-targets activities against other kinases. Through molecular modeling and systematic structure activity relationship (SAR) studies, advanced molecules with high inhibitory potency, reduced off-target activity and minimal efflux were identified as new pan-PIM inhibitors. One example of an early lead, OX01401, was found to inhibit PIMs with nanomolar potency (15 nM for PIM1), inhibit proliferation of two PIM-expressing leukaemic cancer cell lines, MV4-11 and K562, and to reduce intracellular phosphorylation of a PIM substrate in a concentration dependent manner.

Synthesis and Spectroscopic Analysis of Piperine- and Piperlongumine-Inspired Natural Product Scaffolds and Their Molecular Docking with IL-1ß and NF-κB Proteins.

Inspired by the remarkable bioactivities exhibited by the natural products, piperine and piperlongumine, we synthesised eight natural product-inspired analogues to further investigate their structures. For the first time, we confirmed the structure of the key cyclised dihydropyrazolecarbothioamide piperine analogues including the use of two-dimensional (2D) 15N-based spectroscopy nuclear magnetic resonance (NMR) spectroscopy. Prior investigations demonstrated promising results from these scaffolds for the inhibition of inflammatory response via downregulation of the IL-1ß and NF-κB pathway. However, the molecular interaction of these molecules with their protein targets remains unknown. Ab initio calculations revealed the electronic density function map of the molecules, showing the effects of structural modification in the electronic structure. Finally, molecular interactions between the synthesized molecules and the proteins IL-1ß and NF-κB were achieved. Docking results showed that all the analogues interact in the DNA binding site of NF-κB with higher affinity compared to the natural products and, with the exception of 9a and 9b, have higher affinity than the natural products for the binding site of IL-1ß. Specificity for the molecular recognition of 3a, 3c and 9b with IL-1ß through cation-π interactions was determined. These results revealed 3a, 3c, 4a, 4c and 10 as the most promising molecules to be evaluated as IL-1ß and NF-κB inhibitors.

Chemical Methods for N- and O-Sulfation of Small Molecules, Amino Acids and Peptides.

Sulfation of the amino acid residues of proteins is a significant post-translational modification, the functions of which are yet to be fully understood. Current sulfation methods are limited mainly to O-tyrosine (sY), which requires negatively charged species around the desired amino acid residue and a specific sulfotransferase enzyme. Alternatively, for solid-phase peptide synthesis, a de novo protected sY is required. Therefore, synthetic routes that go beyond O-sulfation are required. We have developed a novel route to N-sulfamation and can dial-in/out O-sulfation (without S-sulfurothiolation), mimicking the initiation step of the ping-pong sulfation mechanism identified in structural biology. This rapid, low-temperature and non-racemising method is applicable to a range of amines, amides, amino acids, and peptide sequences.

Small Molecule Glycomimetics Inhibit Vascular Calcification via c-Met/Notch3/HES1 Signalling.

BACKGROUND/AIMS: Vascular calcification represents a huge clinical problem contributing to adverse cardiovascular events, with no effective treatment currently available. Upregulation of hepatocyte growth factor has been linked with vascular calcification, and thus, represent a potential target in the development of a novel therapeutic strategy. Glycomimetics have been shown to interrupt HGF-receptor signalling, therefore this study investigated the effect of novel glycomimetics on osteogenic signalling and vascular calcification in vitro. METHODS: Primary human vascular smooth muscle cells (HVSMCs) were induced by ß-glycerophosphate (ß-GP) and treated with 4 glycomimetic compounds (C1-C4). The effect of ß-GP and C1-C4 on alkaline phosphatase (ALP), osteogenic markers and c-Met/Notch3/HES1 signalling was determined using colorimetric assays, qRT-PCR and western blotting respectively. RESULTS: C1-C4 significantly attenuated ß-GP-induced calcification, as shown by Alizarin Red S staining and calcium content by day 14. In addition, C1-C4 reduced ALP activity and prevented upregulation of the osteogenic markers, BMP-2, Runx2, Msx2 and OPN. Furthermore, ß-GP increased c-Met phosphorylation at day 21, an effect ameliorated by C2 and C4 and the c-Met inhibitor, crizotinib. We next interrogated the effects of the Notch inhibitor DAPT and confirmed an inhibition of ß-GP up-regulated Notch3 protein by C2, DAPT and crizotinib compared to controls. Hes-1 protein upregulation by ß-GP, was also significantly downregulated by C2 and DAPT. GOLD docking analysis identified a potential binding interaction of C1-C4 to HGF which will be investigated further. CONCLUSION: These findings demonstrate that glycomimetics have potent anti-calcification properties acting via HGF/c-Met and Notch signalling.

Medical errors: Healthcare professionals' perspective at a tertiary hospital in Kuwait.

Medical errors are of economic importance and can contribute to serious adverse events for patients. Medical errors refer to preventable events resulting from healthcare interactions, whether these events harm the patient or not. In Kuwait, there is a paucity literature detailing the causes, forms, and risks of medical errors in their state-funded healthcare facilities. This study aimed to explore medical errors, their causes and preventive strategies in a Kuwait tertiary hospital based on the perceptions and experience of a cross-section of healthcare professionals using a questionnaire with 27 open (n = 10) and closed (n = 17) questions. The recruited healthcare professionals in this study included pharmacists, nurses, physicians, dentists, radiographers, hospital administrators, surgeons, nutritionists, and physiotherapists. The collected data were analysed quantitatively using descriptive statistics. A total of 203 participants filled and completed the survey questionnaire. The frequency of medical errors in Kuwait was found to be high at 60.3% ranging from incidences of prolonged hospital stays (32.9%), adverse events and life-threatening complications (32.3%), and fatalities (20.9%). The common medical errors result from incomplete instructions, incorrect dosage, and incorrect route of administration, diagnosis errors, and labelling errors. The perceived causes of these medical errors include high workload, lack of support systems, stress, medical negligence, inadequate training, miscommunication, poor collaboration, and non-adherence to safety guidelines among the healthcare professionals.

BRL3 and AtRGS1 cooperate to fine tune growth inhibition and ROS activation.

Plasma membrane-localized leucine-rich repeat receptor-like kinases directly activates G protein complex via interaction with seven transmembrane domain Regulator of G-protein Signaling 1 (AtRGS1) protein. Brassinosteroid insensitive 1 (BRI1) LIKE3 (BRL3) phosphorylates AtRGS1 in vitro. FRET analysis showed that BRL3 and AtRGS1 interaction dynamics change in response to glucose and flg22. Both BRL3 and AtRGS1 function in glucose sensing and brl3 and rgs1-2 single mutants are hyposensitive to high glucose as well as the brl3/rgs1 double mutant. BRL3 and AtRGS1 function in the same pathway linked to high glucose sensing. Hypocotyl elongation, another sugar-mediated pathway, is also implicated to be partially mediated by BRL3 and AtRGS1 because rgs1-2, brl3-2 and brl3-2/ rgs1-2 mutants share the long hypocotyl phenotype. BRL3 and AtRGS1 modulate the flg22-induced ROS burst and block one or more components positively regulating ROS production because the brl3/rgs1 double mutant has ~60% more ROS production than wild type while rgs1-2 has a partial ROS burst impairment and brl3 has slightly more ROS production. Here, we proposed a simple model where both BRL3 and AtRGS1 are part of a fine-tuning mechanism sensing glucose and flg22 to prevent excess ROS burst and control growth inhibition.

Thiazolidine derivatives as potent and selective inhibitors of the PIM kinase family.

The PIM family of serine/threonine kinases have become an attractive target for anti-cancer drug development, particularly for certain hematological malignancies. Here, we describe the discovery of a series of inhibitors of the PIM kinase family using a high throughput screening strategy. Through a combination of molecular modeling and optimization studies, the intrinsic potencies and molecular properties of this series of compounds was significantly improved. An excellent pan-PIM isoform inhibition profile was observed across the series, while optimized examples show good selectivity over other kinases. Two PIM-expressing leukemic cancer cell lines, MV4-11 and K562, were employed to evaluate the in vitro anti-proliferative effects of selected inhibitors. Encouraging activities were observed for many examples, with the best example (44) giving an IC50 of 0.75µM against the K562 cell line. These data provide a promising starting point for further development of this series as a new cancer therapy through PIM kinase inhibition.

A novel role for small molecule glycomimetics in the protection against lipid-induced endothelial dysfunction: Involvement of Akt/eNOS and Nrf2/ARE signaling.

BACKGROUND: Glycomimetics are a diverse array of saccharide-inspired compounds, designed to mimic the bioactive functions of glycosaminoglycans. Therefore, glycomimetics represent a unique source of novel therapies to target aberrant signaling and protein interactions in a wide range of diseases. We investigated the protective effects of four newly synthesized small molecule glycomimetics against lipid-induced endothelial dysfunction, with an emphasis on nitric oxide (NO) and oxidative stress. METHODS: Four aromatic sugar mimetics were synthesized by the stepwise transformation of 2,5-dihydroxybenzoic acid to derivatives (C1-C4) incorporating sulfate groups to mimic the structure of heparan sulfate. RESULTS: Glycomimetic-treated human umbilical vein endothelial cells (HUVECs) were exposed to palmitic acid to model lipid-induced oxidative stress. Palmitate-induced impairment of NO production was restored by the glycomimetics, through activation of Akt/eNOS signaling. Furthermore, C1-C4 significantly inhibited palmitate-induced reactive oxygen species (ROS) production, lipid peroxidation, and activity and expression of NADPH oxidase. These effects were attributed to activation of the Nrf2/ARE pathway and downstream activation of cellular antioxidant and cytoprotective proteins. In ex vivo vascular reactivity studies, the glycomimetics (C1-C4) also demonstrated a significant improvement in endothelium-dependent relaxation and decreased ROS production and NADPH oxidase activity in isolated mouse thoracic aortic rings exposed to palmitate. CONCLUSIONS: The small molecule glycomimetics, C1-C4, protect against lipid-induced endothelial dysfunction through up-regulation of Akt/eNOS and Nrf2/ARE signaling pathways. Thus, carbohydrate-derived therapeutics are a new class of glycomimetic drugs targeting endothelial dysfunction, regarded as the first line of defense against vascular complications in cardiovascular disease.

A fragment-based approach applied to a highly flexible target: Insights and challenges towards the inhibition of HSP70 isoforms.

The heat shock protein 70s (HSP70s) are molecular chaperones implicated in many cancers and of significant interest as targets for novel cancer therapies. Several HSP70 inhibitors have been reported, but because the majority have poor physicochemical properties and for many the exact mode of action is poorly understood, more detailed mechanistic and structural insight into ligand-binding to HSP70s is urgently needed. Here we describe the first comprehensive fragment-based inhibitor exploration of an HSP70 enzyme, which yielded an amino-quinazoline fragment that was elaborated to a novel ATP binding site ligand with different physicochemical properties to known adenosine-based HSP70 inhibitors. Crystal structures of amino-quinazoline ligands bound to the different conformational states of the HSP70 nucleotide binding domain highlighted the challenges of a fragment-based approach when applied to this particular flexible enzyme class with an ATP-binding site that changes shape and size during its catalytic cycle. In these studies we showed that Ser275 is a key residue in the selective binding of ATP. Additionally, the structural data revealed a potential functional role for the ATP ribose moiety in priming the protein for the formation of the ATP-bound pre-hydrolysis complex by influencing the conformation of one of the phosphate binding loops.

Direct Modulation of Heterotrimeric G Protein-coupled Signaling by a Receptor Kinase Complex.

Plants and some protists have heterotrimeric G protein complexes that activate spontaneously without canonical G protein-coupled receptors (GPCRs). In Arabidopsis, the sole 7-transmembrane regulator of G protein signaling 1 (AtRGS1) modulates the G protein complex by keeping it in the resting state (GDP-bound). However, it remains unknown how a myriad of biological responses is achieved with a single G protein modulator. We propose that in complete contrast to G protein activation in animals, plant leucine-rich repeat receptor-like kinases (LRR RLKs), not GPCRs, provide this discrimination through phosphorylation of AtRGS1 in a ligand-dependent manner. G protein signaling is directly activated by the pathogen-associated molecular pattern flagellin peptide 22 through its LRR RLK, FLS2, and co-receptor BAK1.

Exploiting Protein Conformational Change to Optimize Adenosine-Derived Inhibitors of HSP70.

HSP70 is a molecular chaperone and a key component of the heat-shock response. Because of its proposed importance in oncology, this protein has become a popular target for drug discovery, efforts which have as yet brought little success. This study demonstrates that adenosine-derived HSP70 inhibitors potentially bind to the protein with a novel mechanism of action, the stabilization by desolvation of an intramolecular salt-bridge which induces a conformational change in the protein, leading to high affinity ligands. We also demonstrate that through the application of this mechanism, adenosine-derived HSP70 inhibitors can be optimized in a rational manner.