Stable Molecular Complexes Research Articles

In silico approach of Garcinia mangostana and Ortosiphon stamineus to restore adipokines level as drug candidate for metabolic syndrome

Background: Metabolic syndrome is a group of metabolic disorders due to dysfunctional adipose tissue. Adipose tissue is an endocrine organ that secretes many pro-inflammatory and anti-inflammatory adipokines. Garcinia mangostana and Orthosiphon stamineus have demonstrated various pharmacological effects, including antidiabetic, anti-dyslipidemia, antiobesity, antioxidant, and anti-inflammatory properties. Objective: This study aimed to analyse the interaction of phytochemical compounds from Garcinia mangostana and Orthosiphon stamineus in decreasing levels of pro-inflammatory adipokines while increasing levels of anti-inflammatory adipokines. Method: This research is an in silico study of phytochemical compounds from Garcinia mangostana and Orthosiphon stamineus retrieved from PubChem and HMDB. Adipokines as target proteins were obtained from RCSB and UniProt. Result: Mangostanin, mangostanol, and mangostinone from Garcinia mangostana, as well as ladanein, salveginin, sinensetin, and rosmarinic acid from Orthosiphon stamineus, exhibited stable molecular complexes compared to other compounds. Conclusion: Phytochemical compounds from Garcinia mangostana and Orthosiphon stamineus show potential as candidates for metabolic syndrome drugs by restoring adipokine levels. However, further research is still needed.

Comparative docking and molecular dynamics studies of molnupiravir (EIDD-2801): implications for novel mechanisms of action on influenza and SARS-CoV-2 protein targets

Molnupiravir (EIDD-2801) (MLN) is an oral antiviral drug for COVID-19 treatment, being integrated into viral RNA through RNA-dependent RNA polymerase (RdRp). Upon ingestion, MLN is transformed into two active metabolites: β-d-N4-hydroxycytidine (NHC) (EIDD-1931) in the host plasma, and EIDD-1931-triphosphate (MTP) within the host cells. However, recent studies provide increasing evidence of MLN’s interactions with off-target proteins beyond the viral genome, suggesting that the complete mechanisms of action of MLN remain unclear. The aim of this study was therefore to investigate the molecular interactions of MLN in the form of NHC and MTP with the non-RNA structural components of avian influenza (hemagglutinin, neuraminidase) and SARS-CoV-2 (spike glycoprotein, Mpro, and RdRp) viruses and to elucidate whether these two metabolites possess the ability to form stable complexes with these major viral components. Molecular docking of NHC and MTP was performed using AutoDock 4.2.6 and the obtained protein-drug complexes were submitted to 200-ns molecular dynamics simulations in triplicate with subsequent free energy calculations using GROMACS. Docking scores, molecular dynamics and MM/GBSA results showed that MTP was tightly bound within the active site of SARS-CoV-2 RdRp and remained highly stable throughout the 200-ns simulations. Besides, it was also shown that NHC and MTP formed moderately-to-highly stable molecular complexes with off-target receptors hemagglutinin, neuraminidase and Mpro, but rather weak interactions with spike glycoprotein. Our computational findings suggest that NHC and MTP may directly inhibit these receptors, and propose that additional studies on the off-target effects of MLN, i.e. real-time protein binding assays, should be performed. Communicated by Ramaswamy H. Sarma

Electrochemistry and Spin‐Crossover Behavior of Fluorinated Terpyridine‐Based Co(II) and Fe(II) Complexes

AbstractDue to their ability to form stable molecular complexes that have tailor‐made properties, terpyridine ligands are of great interest in chemistry and material science. In this regard, we prepared two terpyridine ligands with two different fluorinated phenyl rings on the backbone. The corresponding CoII and FeII complexes were synthesized and characterized by single‐crystal X‐ray structural analysis, electrochemistry and temperature‐dependent SQUID magnetometry. Single crystal X‐ray diffraction analyses at 100 K of these complexes revealed Co−N and Fe−N bond lengths that are typical of low spin CoII and FeII centers. The metal centers are coordinated in an octahedral fashion and the fluorinated phenyl rings on the backbone are twisted out of the plane of the terpyridine unit. The complexes were investigated with cyclic voltammetry and UV/Vis‐NIR spectroelectrochemistry. All complexes show a reversible oxidation and several reduction processes. Temperature dependent SQUID magnetometry revealed a gradual thermal SCO behavior in two of the complexes, while EPR spectroscopy provided further insights on the electronic structure of the metal complexes, as well as site of reduction.

Water-Soluble Dicationic Deuteroporphyrin Derivative for Antimicrobial PDT: Singlet Oxygen Generation, Passive Carrier Interaction and Nosocomial Bacterial Strains Photoinactivation

Multidrug resistance of pathogenic microflora is a serious threat to the modern community looking for new approaches to treating superinfections. In this sense, antimicrobial photodynamic therapy (aPDT) is an effective and safe technique considered to be a promising alternative or an important supplement to the traditional clinically applied methods for inactivating antibiotic resistant pathogens. Macroheterocyclic photosensitizers (PS) of three generations are proposed for clinical practice. They are known as the key compounds for PDT able to be localized selectively in microbial cells and to be activated with the red light producing toxic reactive oxygen species (ROS). However, these neutral and anionic PSs possess low affinity towards the outer lipopolysaccharide membrane of Gram-negative bacteria and, consequently, poor ability to kill these pathogens under irradiation. In contrast, cationic PSs containing one or more charged groups, especially those bound to an appropriate carrier, provide efficient inactivation of microorganisms. In this paper, we focus on the study of photophysics, aggregation and photoinduced antimicrobial activity of the water-soluble derivative of deuteroporphyrin-IX, a blood group porphyrin, bearing two cationic trialkylammonium fragments. This potential photosensitizing agent is found to generate singlet oxygen in a non-polar environment and forms stable nano-sized molecular complexes with passive non-ionic carrier Tween 80, localizing in an aqueous surfactant solution as a non-aggregated form in the surface micellar layer. Two different modes of PS/Tween 80 binding characterized by their own stability constants and interaction stoichiometry are observed. Microbiological experiments clearly demonstrate that the increased permeability of the outer bacterial membrane caused by the application of the intramicellar form of the photosensitizer or addition of some potentiation agents leads to pronounced light phototoxicity of the pigment against antibiotic-resistant nosocomial strains of Gram-negative bacterial pathogens.

Protein Interactome Profiling of Stable Molecular Complexes in Biomaterial Lysate.

Most proteins function as part of various complexes, forming via stable and dynamic protein-protein interactions (PPIs). The profiling of PPIs expands the fundamental knowledge about the structures, functions, and regulation patterns of protein complexes and intracellular molecular machineries. Protein interactomics aims at solving three main tasks: (1) identification of protein partners and parts of complex intracellular structures; (2) analysis of PPIs parameters (affinity, molecular-recognition specificity, kinetic rate constants, and thermodynamic-parameters determination); (3) the study of the functional role of novel PPIs. The purpose of this work is to update the current state and prospects of multi-omics approaches to profiling of proteins involved in the formation of stable complexes. Methodological paradigm includes a development of protein-extraction and -separation techniques from tissues or cellular lysates and subsequent identification of proteins using mass-spectrometry analysis. In addition, some aspects of authors' experimental platforms, based on high-performance size-exclusion chromatography, procedures of molecular fishing, and protein identification, as well as the possibilities of interactomic taxonomy of each protein, are discussed.

Integrative Expression, Survival Analysis and Cellular miR-2909 Molecular Interplay in MRN Complex Check Point Sensor Genes (MRN-CSG) Involved in Breast Cancer

BackgroundBreast cancer, an emerging global challenge, is evidenced by recent studies of miRNAs involvement in DNA repair gene variants (MRE11, RAD50, and NBN as checkpoint sensor genes (CSG) – MRN-CSG). The identification of various mutations in MRN-CSG and their interactions with miRNAs is still not understood. The emerging studies of miR-2909 involvement in other cancers led us to explore its role as molecular mechanistic marker in breast cancer. Materials and MethodsThe genomic and proteomic data of MRN-CSG of breast cancer patients (8426 samples) was evaluated to identify the mutation types linked with the patient's survival rate. Additionally, molecular, 3D-structural and functional analysis was performed to identify miR-2909 as regulator of MRN-CSG. ResultsThe genomic and proteomic data analysis shows genetic alterations with majority of missense mutations [RAD50 (0.7%), MRE11 (1.5%), and NBN (11%)], though with highest MRE11 mRNA expression in invasive ductal breast carcinoma as compared to other breast cancer types. The Kaplan–Meier survival curves suggest higher survival rate for unaltered groups as compared to the altered group. Network analysis and disease association of miR-2909 and MRN-CSG shows strong interactions with other partners. The molecular hybridization between miR-2909-RAD50 and miR-2909-MRE11 complexes showed thermodynamically stable structures. Further, argonaute protein, involved in RNA silencing, docking studies with miR-MRE11-mRNA and miR-RAD50-mRNA hybridized complexes showed strong binding affinity. ConclusionThe results suggest that miR-2909 forms strong thermodynamically stable molecular hybridized complexes with MRE11 and RAD50 mRNAs which further strongly interacts with argonaute protein to show potential molecular mechanistic role in breast cancer.

Can We Merge the Weak and Strong Tetrel Bonds? Electronic Features of Tetrahedral Molecules Interacted with Halide Anions.

Using the orbital-free quantum crystallography approach, we have disclosed the quantitative trends in electronic features for bonds of different strengths formed by tetrel (Tt) atoms in stable molecular complexes consisting of electrically neutral tetrahedral molecules and halide anions. We have revealed the role of the electrostatic and exchange-correlation components of the total one-electron static potential that are determined by the equilibrium atomic structure and by kinetic Pauli potential, which reflects the spin-dependent electron motion features of the weak and strong bonds. The gap between the extreme positions in the electrostatic and total static potentials along the line linking the Tt atom and halide anion is wide for weak bonds and narrow for strong ones. It is in very good agreement with the number of minima in the Pauli potential between the bounded atoms. This gap exponentially correlates with the exchange-correlation potential in various series with a fixed nucleophilic fragment. A criterion for categorizing the noncovalent tetrel bonds (TtB) based on the potential features is suggested.

Pre-miRNA-149 G-quadruplex as a molecular agent to capture nucleolin

One of the most significant challenges in capturing and detecting biomarkers is the choice of an appropriate biomolecular receptor. Recently, RNA G-quadruplexes emerged as plausible receptors due to their ability to recognize with high-affinity proteins. Herein, we have unveiled and characterized the capability of the precursor microRNA 149 to form a G-quadruplex structure and determined the role that some ligands may have in its folding and binding capacity to nucleolin. The G-quadruplex formation was induced by K+ ions and stabilized by ligands, as demonstrated by nuclear magnetic resonance and circular dichroism experiments. Surface plasmon resonance measurements showed a binding affinity of precursor microRNA 149 towards ligands in the micromolar range (10−5–10−6 M) and a strong binding affinity to nucleolin RNA-binding domains 1 and 2 (8.38 × 10−10 M). Even in the presence of the ligand PhenDC3, the binding remains almost identical and in the same order of magnitude (4.46 × 10−10 M). The molecular interactions of the RNA G-quadruplex motif found in precursor miRNA 149 (5′-GGGAGGGAGGGACGGG- 3′) and nucleolin RNA-binding domains 1 and 2 were explored by means of molecular docking and molecular dynamics studies. The results showed that RNA G-quadruplex binds to a cavity between domains 1 and 2 of the protein. Then, complex formation was also evaluated through polyacrylamide gel electrophoresis. The results suggest that precursor microRNA 149/ligands and precursor microRNA 149/nucleolin RNA-binding domains 1 and 2 form stable molecular complexes. The in vitro co-localization of precursor microRNA 149 and nucleolin in PC3 cells was demonstrated using confocal microscopy. Finally, a rapid and straightforward microfluidic strategy was employed to check the ability of precursor microRNA 149 to capture nucleolin RNA-binding domains 1 and 2. The results revealed that precursor microRNA 149 can capture nucleolin RNA-binding domains 1 and 2 labeled with Fluorescein 5-isothiocyanate in a concentration-dependent manner, but PhenDC3 complexation seems to decrease the ability of precursor microRNA 149 to capture the protein. Overall, our results proved the formation of the G-quadruplex structure in the precursor microRNA 149 and the ability to recognize and detect nucleolin. This proof-of-concept study could open up a new framework for developing new strategies to design improved molecular receptors for capture and detection of nucleolin in complex biological samples.

Polymers Sorption Properties towards Photosynthetic Pigments and Fungicides.

In the present work, extraction with a solvent (cold acetone) was used to extract the assimilation pigments from spinach leaves. Then, the sorption capacity of selected plastics granules (polyvinyl chloride—PVC, polypropylene—PP, polyethylene—PE of different densities) was tested for the selective isolation of chlorophylls. Quantification of chlorophylls by HPLC (Zorbax Eclipse XDB-C18 column, the mobile phase: Acetonitrile/methanol/ethyl acetate 6:2:2, v/v) was based on chlorophyll-a content as the most common chlorophyll. The performed experiments prove that PVC containing electronegative chlorine exhibits favorable interactions toward chlorophyll by creating stable molecular complexes. The Fourier Transform Raman Spectroscopy (FT-Raman) and the molecular modeling were used to elucidate the structure of the created complexes. The optimal extraction requirements, the mass of sorbent, water-acetone ratio, time, and the composition of the elution solvent were all established. The optimized extraction conditions ensured a maximum extraction yield of chlorophylls of 98%. The chlorophyll-rich sorbent was re-extracted by acetone, leading to the recovery of 91% of chlorophylls in one step, adding the possibility of its re-use. The proposed effective and ecological method of obtaining the green dye from plants is cheap, simple, and efficient, avoiding organic solvents, utilizing the most widely used synthetic polymers in the world, being products difficult for utilization. The possibility to remove chosen fungicides cyprodinil, chlorothalonil, and thiabendazone from plant extract by PVC was also examined. The described method proposes a new application of synthetic polymers, which meets the criteria of sustainable green chemistry, simultaneously reaching the growing demand for pure natural compounds in the pharmaceutical and food industries.

Interaction of cationic chlorin photosensitizers with non-ionic surfactant Tween 80

The interaction between cationic chlorophyll photosensitizers (PSs) for antimicrobial photodynamic therapy and non-ionic surfactant Tween 80 as a potential carrier system was studied using absorption and fluorescence spectroscopy. The results, analyzed in terms of our approach and the Stern–Volmer approach, indicate that all three PSs form stable molecular complexes with Tween 80, the PS molecules being located at the periphery of surfactant micelles next to hydrophilic head groups. The higher the charge of the macrocyclic cation, the stronger the interaction of PS with the surfactant.

Inclusion complexes between cisplatin and oxidized carbon nanostructures: A theoretical approach

The toxicity of inclusion compounds formed by carbon nanostructures depends on its functionalized surface, use of solvents, dosage and other properties. Molecular modeling has potentially contributed to the understanding of the chemical nature of the formation of these systems and allows advancement in studies of the mechanism of transport, release of drugs and their biological implications. This work reports a quantum chemical investigation of the inclusion complexes formation between oxidized carbon nanotube (CNTox)/nanocone (CNCox) structure and cisplatin molecule, using the density functional theory (DFT) with the B3LYP functional and 6–31G(d,p)/LanL2DZ standard basis sets. Our results indicate that the cDDP@CNTox (inclusion complex – cisplatin into oxidized carbon nanotube) and cDDP@CNCox (inclusion complex – cisplatin into oxidized carbon nanocone) systems form stable molecular complexes that can be used as drug delivery devices. Our theoretical simulation of molecular spectra (IR, Raman and 1H NMR) reveals substantial changes due to complex formation that can be easily experimentally observed.

Synthesis, Characterization, and DFT Analysis of Bis-Terpyridyl-Based Molecular Cobalt Complexes.

Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions. The corresponding cobalt(II) complexes were synthesized and fully characterized by elemental analysis, single-crystal X-ray crystallography, mass spectrometry, and UV-vis, 1H NMR, and Fourier transform infrared (FT-IR) spectroscopy as well as by cyclic voltammetry (CV). Density functional theory (DFT) calculations were performed to investigate the electronic structure of all the Co(II) bis-terpyridyl molecular complexes. In this work, we show that terpyridine ligand functionalization allows tuning the redox potentials of the Co(III)/Co(II), Co(II)/Co(I), and Co(I)/Co(I) (tpy)•- couples over a 1 V range.

Investigations on the frontier orbitals of FeFn (n = 1–6) superhalogen complexes and prediction of novel salt series Li-(FeFn)

First-principles calculations predict that atomic iron (Fe) combines with fluorine (F) to produce stable molecular complexes having the form FeFn (n=1–6) and the species with n≥3 exhibit superhalogen properties. Electron affinities of the complexes are found to increase successively upto 8.20eV for FeF6. The unusual properties of these complexes are due to the involvement of inner shell 3d-electrons, which allow FeFn complexes to belong to the class of superhalogens and also due to the tendency of Fe to have valency that can exceed the value of 3. Quantum chemical calculations were carried out using an all-electron linear combination of atomic orbitals scheme within the density functional theory (DFT) framework utilizing the popular B3LYP (Becke, three-parameter, Lee–Yang–Parr) exchange correlation functional. Analysis of HOMO-LUMO gaps, molecular orbitals and binding energies of these complexes indicate that the FeFn complexes are stable. Population analysis of molecular orbitals was also carried out to determine the percentage (%) contribution of Fe and F atoms to the frontier orbitals (LUMO and HOMO). The orbital overlap population (OOP) diagrams provide information related to bonding and anti-bonding nature of overlap in the molecular orbitals. The principle of maximum hardness was applied to determine the relative stability of the complexes. Also, the stability and viability of novel salt series Li-(FeFn) has been tested by analyzing the molecules Li-(FeF4), Li-(FeF5) and Li-(FeF6) in detail.

Structure of hydrogen fluoride complexes with diethylketone in a HF–Et2CO solution

The optimal configurations and the vibrational spectra of heteroassociates (HAs) of hydrogen fluoride and diethylketone molecules with 1:1, 2:2, 4:1, and 8:2 compositions are calculated using the density functional theory (B3LYP/6-31++G(d,p)). A comparison of the results of calculations and the known experimental data reveal that the following stable hydrogen-bonded molecular complexes are formed in HF–Et2CO solutions: the C2h symmetry cyclic heterotetramer (HF)2∙(Et2CO)2 and the tricyclic HA (HF)8∙(Et2CO)2 formed based on the heterotetramer by the binding of two (HF)3 moieties. It is shown that it is appropriate to decompose the spectral curve into the Gaussian functions or the Lorentzian functions to determine the frequencies and the integrated intensities of broad and overlapped IR bands. The first type of the decomposition enables one to estimate more correctly the values of the band frequencies, and the second type makes it possible to find more correctly the band intensities.

Solid-state flurbiprofen and methyl-β-cyclodextrin inclusion complexes prepared using a single-step, organic solvent-free supercritical fluid process

The aim of this study was to enhance the apparent solubility and dissolution properties of flurbiprofen through inclusion complexation with cyclodextrins. Especially, the efficacy of supercritical fluid technology as a preparative technique for the preparation of flurbiprofen–methyl-β-cyclodextrin inclusion complexes was evaluated. The complexes were prepared by supercritical carbon dioxide processing and were evaluated by solubility, differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, practical yield, drug content estimation and in vitro dissolution studies. Computational molecular docking studies were conducted to study the possibility of molecular arrangement of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin. The studies support the formation of stable molecular inclusion complexes between the drug and cyclodextrin in a 1:1 stoichiometry. In vitro dissolution studies showed that the dissolution properties of flurbiprofen were significantly enhanced by the binary mixtures prepared by supercritical carbon dioxide processing. The amount of flurbiprofen dissolved into solution alone was very low with 1.11±0.09% dissolving at the end of 60min, while the binary mixtures processed by supercritical carbon dioxide at 45°C and 200bar released 99.39±2.34% of the drug at the end of 30min. All the binary mixtures processed by supercritical carbon dioxide at 45°C exhibited a drug release of more than 80% within the first 10min irrespective of the pressure employed. The study demonstrated the single step, organic solvent-free supercritical carbon dioxide process as a promising approach for the preparation of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin in solid-state.

ChemInform Abstract: Molecular Assemblies Based on Strong Axial Coordination in Metal Complexes of Saddle‐Distorted Dodecaphenylporphyrins

AbstractReview: 48 refs.

Molecular assemblies based on strong axial coordination in metal complexes of saddle-distorted dodecaphenylporphyrins

In this mini-review, we have highlighted our works on metal complexes having saddle-distorted dodecaphenylporphyrin (DPP) and its derivative as ligands in the light of enhancement of the Lewis acidity of a metal center coordinated by the porphyrin. The important point through this mini-review is ill-overlap of the out-of-plane lone pairs of pyrrole nitrogen atoms with σ-orbitals of the metal center bound to the saddle-distorted porphyrin core. The enhanced Lewis acidity of the central metal ions enabled us to construct stable molecular complexes through axial coordination using metal–DPP (M(DPP)) moieties ( M = Mo V or Sn IV ) and molecular or ionic entities with Lewis-basic coordination sites, including Keggin-type polyoxometallates (POM), which are known to have weak Lewis basicity and thus hard to coordinate to metal ions. A discrete 1:2 complex with a Ru -substituted POM performs catalytic substrate oxidation reactions in organic solvents. A 1:1 complex between Sn IV ( DPP ) and a Keggin-type POM exhibited photoinduced electron transfer, in which the Sn IV ( DPP ) moiety acts as an electron donor and the POM as an electron acceptor. Besides POM, other electron acceptors, including μ3-oxo trinuclear Ru III clusters and anthraquinone, having carboxyl groups as a linker unit also formed stable complexes with DPP-metal complexes as axial ligands to perform photoinduced electron transfer. Successful photoreactions of the M(DPP)-acceptor complexes are mainly enabled by the enhanced Lewis acidity of the DPP-metal complexes for the stabilization of the assemblies and also by lowering the oxidation potential of the porphyrin ligand to gain larger driving force of electron transfer to form an electron-transfer state with avoiding intersystem crossing. The stability and photochemical behavior are in sharp contrast to those for metal complexes with planar porphyrins as ligands.

Pathogenic Mechanisms in Lupus Nephritis: Nucleosomes Bind Aberrant Laminin β1 With High Affinity and Colocalize in the Electron‐Dense Deposits

Apoptotic nucleosomes are structurally and immunologically involved in lupus nephritis. The purpose of this study was to examine the expression and function of laminins and their interactions with nucleosomes in the kidneys of patients with lupus nephritis, using surface plasmon resonance (SPR) analysis. SPR interaction analysis was used to quantify the strength of laminin-nucleosome interactions. Electron microscopy techniques were used to determine in vivo colocalization of IgG, chromatin, and laminin β1, as well as to characterize nucleosome-laminin interactions in vitro. Nucleosomes were found to possess high affinity for laminin β1-containing laminins and to have the potential to form stable molecular complexes with these structures. In vivo, laminin β1 was aberrantly expressed in the glomerular basement membrane (GMB) of lupus nephritis patients, and in situ, it acted as a nucleosome ligand, selectively colocalizing with nucleosomes within electron-dense deposits (EDDs). Normal adult laminin 11, which contains laminin β2, did not bind nucleosomes, and it did not colocalize in vivo with the nucleosomes in the nephritic GBM. In addition, TGFβ1 was expressed by the glomerular mesangium, glomerular endothelial cells, and by podocytes in patients with lupus nephritis. It was trapped in situ within EDDs by an as-yet-unknown ligand. As was recently described in a transgenic mouse model, paracrine kidney glomerular TGFβ1 may thereby contribute to the development of glomerulopathy via the induction of laminin β1 incorporation in the GBM, whereas systemic blood vessel-derived TGFβ1 could be trapped during filtration. Our findings of the specific high-affinity binding of nucleosomes to aberrantly expressed laminin β1 in the GBM and their colocalization in the GBM may explain important features of the initial steps in the pathogenesis of lupus nephritis, the planted antigen hypothesis.

Differential, dominant activation and inhibition of Notch signalling and APP cleavage by truncations of PSEN1 in human disease

PRESENILIN1 (PSEN1) is the major locus for mutations causing familial Alzheimer's disease (FAD) and is also mutated in Pick disease of brain, familial acne inversa and dilated cardiomyopathy. It is a critical facilitator of Notch signalling and many other signalling pathways and protein cleavage events including production of the Amyloidβ (Aβ) peptide from the AMYLOID BETA A4 PRECURSOR PROTEIN (APP). We previously reported that interference with splicing of transcripts of the zebrafish orthologue of PSEN1 creates dominant negative effects on Notch signalling. Here, we extend this work to show that various truncations of human PSEN1 (or zebrafish Psen1) protein have starkly differential effects on Notch signalling and cleavage of zebrafish Appa (a paralogue of human APP). Different truncations can suppress or stimulate Notch signalling but not Appa cleavage and vice versa. The G183V mutation possibly causing Pick disease causes production of aberrant transcripts truncating the open reading frame after exon 5 sequence. We show that the truncated protein potentially translated from these transcripts avidly incorporates into very stable Psen1-dependent higher molecular weight complexes and suppresses cleavage of Appa but not Notch signalling. In contrast, the truncated protein potentially produced by the P242LfsX11 acne inversa mutation has no effect on Appa cleavage but, unexpectedly, enhances Notch signalling. Our results suggest novel hypotheses for the pathological mechanisms underlying these diseases and illustrate the importance of investigating the function of dominant mutations at physiologically relevant expression levels and in the normally heterozygous state in which they cause human disease rather than in isolation from healthy alleles.

Archaeal β-CASP ribonucleases of the aCPSF1 family are orthologs of the eukaryal CPSF-73 factor

Bacterial RNase J and eukaryal cleavage and polyadenylation specificity factor (CPSF-73) are members of the β-CASP family of ribonucleases involved in mRNA processing and degradation. Here we report an in-depth phylogenomic analysis that delineates aRNase J and archaeal CPSF (aCPSF) as distinct orthologous groups and establishes their repartition in 110 archaeal genomes. The aCPSF1 subgroup, which has been inherited vertically and is strictly conserved, is characterized by an N-terminal extension with two K homology (KH) domains and a C-terminal motif involved in dimerization of the holoenzyme. Pab-aCPSF1 (Pyrococcus abyssi homolog) has an endoribonucleolytic activity that preferentially cleaves at single-stranded CA dinucleotides and a 5′–3′ exoribonucleolytic activity that acts on 5′ monophosphate substrates. These activities are the same as described for the eukaryotic cleavage and polyadenylation factor, CPSF-73, when engaged in the CPSF complex. The N-terminal KH domains are important for endoribonucleolytic cleavage at certain specific sites and the formation of stable high molecular weight ribonucleoprotein complexes. Dimerization of Pab-aCPSF is important for exoribonucleolytic activity and RNA binding. Altogether, our results suggest that aCPSF1 performs an essential function and that an enzyme with similar activities was present in the last common ancestor of Archaea and Eukarya.