Amino Acid Sequence Research Articles

First molecular detection of adenoviruses in bats from an urban Atlantic Forest in Rio de Janeiro, Brazil

Bats comprise one of the most diverse and abundant groups of mammals in the world and host a significant viral diversity with zoonotic potential. Bat adenoviruses (bat AdVs), members of the family Adenoviridae, have been detected in several bat species, suggesting that bats are natural reservoirs. Here, faeces and rectal/anal-swabs were collected from 321 bats of an urban Atlantic Forest remnant from Rio de Janeiro, during 2019–2022, and screened for bat AdV nucleic acid with PCR. The positivity of bat AdVs was 3.7 % (12/321). Twelve individuals of four bat species were infected: Artibeus lituratus (66.7 %; 8/12), Desmodus rotundus (8.3 %; 1/12), Platyrrhinus lineatus (16.7 %; 2/12), and Sturnira lilium (8.3 %; 1/12). Phylogenetic analysis based on nucleotide and amino acid sequences showed that the detected bat AdVs clustered into four clades corresponding to the host species, identifying the presence of two potentially new bat adenoviruses. This is the first report of bat AdV detected in Platyrrhinus lineatus.

Ameloblastin binding to biomimetic models of cell membranes – A continuum of intrinsic disorder

ObjectiveA 37-residue amino acid sequence corresponding to the segment encoded by exon-5 of murine ameloblastin (Ambn), AB2 (Y67-Q103), has been implicated with membrane association, ameloblastin self-assembly, and amelogenin-binding. Our aim was to characterize, at the residue level, the structural behavior of AB2 bound to chemical mimics of biological membranes using NMR spectroscopy. DesignTo better define the structure of AB2 using NMR-based methods, recombinant 13C- and 15N-labelled AB2 (*AB2) was prepared and data collected free in solution and with deuterated dodecylphosphocholine (dPC) micelles, deuterated bicelles, and both small and large unilamellar vesicles. ResultsAmide chemical shift and intensity perturbations observed in 1H-15N HSQC spectra of *AB2 in the presence of bicelles and dPC micelles suggest that a region of *AB2, S6-E36 (murine Ambn S68 – E98), associates with the membrane biomimetics. A CSI-3 analysis of the NMR chemical shift assignments for *AB2 free in solution and bound to dPC micelles indicated the peptide remains disordered except for the adoption of a short, 12-residue α-helix, F10-G21 (murine Ambn F72-G83). In dPC micelles, the NOE NMR data was void of patterns characteristic of long-lived helical structure indicating this helix was transient in nature. ConclusionsA continuum of intrinsic disorder in the membrane-bound state may be responsible for ameloblastin’s ability to dynamically interact with multiple partners at the same site during amelogenesis.

CoSEF-DBP: Convolution scope expanding fusion network for identifying DNA-binding proteins through bilingual representations

Precisely recognizing DNA-binding proteins (DBPs) from sequences is crucial for a profound comprehension of the mechanisms governing protein-DNA interactions in various cellular processes. However, traditional in-silico methods for DBP identification encounter several challenges, such as time-consuming evolutionary modeling based on multiple sequence alignments, and intricate feature engineering associated with machine or deep learning approaches. In this paper, we introduce a novel end-to-end predictor for identifying DNA-binding proteins without intricate feature engineering, which innovatively enriches the semantics of amino acid sequences through the fusion of bilingual representations derived from distinct language models. We further design a convolution scope expanding (CoSE) module to widen the receptive fields of convolution kernels, thereby forming protein-level CoSE representation sequences. These representations are subsequently integrated via BiLSTM in conjunction with a simplified capsule network, enhancing the hierarchical feature extraction capability. Extensive experiments confirm that our model surpasses existing baselines across diverse benchmark datasets, notably achieving at least a 5.1% improvement in MCC value on the UniSwiss dataset.

Safety evaluation of the food enzyme α-amylase from the non-genetically modified Bacillus amyloliquefaciens strain UN-01.

The food enzyme α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1) is produced with the non-genetically modified microorganism Bacillus amyloliquefaciens strain UN-01 by Nagase (Europa) GmbH. The production strain qualified for the qualified presumption of safety approach and no issues of concern arose from the production process of the food enzyme, therefore, the Panel considered that toxicological studies were unnecessary. It is intended to be used in five food manufacturing processes. Since residual amounts of total organic solids (TOS) are removed during two processes, dietary exposure was calculated only for the remaining three food manufacturing processes. It was estimated to be up to 0.434 mg TOS/kg body weight per day in European populations. A search for homology of the amino acid sequence of the food enzyme to known allergens was made and one match with a respiratory allergen was found. Known sources of food allergens were used in the food enzyme manufacturing process. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

β-Cyclodextrin Derivatives Bind Aromatic Side Chains of the Cyclic Peptide Lanreotide

Cyclodextrin complexation has a potential to modulate the physicochemical properties of peptide drugs. The ability of peptides to form an inclusion complex can be influenced by factors such as size, amino acid sequence of peptide and the size and charge of the cyclodextrin cavity. In this study, the inclusion complexes of cyclic peptide drug lanreotide acetate with two common β-cyclodextrin derivatives, Sulfobutyl ether β-CD (SBEβ-CD) and hydroxypropyl β-CD (HPβ-CD) were investigated. NMR spectroscopy was used to examine the interaction between β-cyclodextrin derivatives and specific residues of lanreotide. It was observed that the hydrophobic side chain of aromatic residues in the lanreotide sequence can be fit into the cavity of both β-cyclodextrin derivatives. Additionally, NMR revealed a lower diffusion coefficient and higher hydrodynamic radius of complex, indicative of binding to the cavities. Each aromatic residue was individually studied by substituting alanine in lanreotide to measure its association binding with both β-cyclodextrin derivatives. The alanine-substitute study indicated a stronger binding of SBEβ-CD to Lanreotide compared to HPβ-CD. Docking studies suggested that the 1:1 inclusion complex is more favorable than higher order complexes due to the steric hindrance and size considerations. The docking analysis indicated the stable conformation of all three aromatic side chains with both β-cyclodextrin derivatives, SBEβ-CDand HPβ-CD.

Transcription factor networks drive perforin activity in the anti-bacterial immune response of tilapia

Perforin, produced by natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), is one of the effectors of cell-mediated cytotoxicity (CMC) in vertebrates, playing a paramount role in killing target cells. However, whether and how perforin is involved in adaptive immune responses in early vertebrates remains unclear. Using Nile tilapia (Oreochromis niloticus) as a model, we investigated the characteristics of perforin in early vertebrates. Oreochromis niloticus perforin (OnPRF) possesses 2 conserved functional domains, membrane attack complex/perforin (MACPF) and protein kinase C conserved region 2 (C2) domains, although they share low amino acid sequence similarity with other homologs. OnPRF was widely expressed in various immune tissues and could respond to lymphocyte activation and T-cell activation in vitro at both the transcriptional and protein levels, indicating that it may be involved in adaptive immune responses. Furthermore, after infection with Edwardsiella piscicida and Aeromonas hydrophila, the mRNA and protein levels of OnPRF were significantly up-regulated within the adaptive immune response period. Additionally, we revealed that many transcription factors were involved in the transcriptional regulation of OnPRF, including p65, c-Fos, c-Jun, STAT1 and STAT4, and there was a synergy among these transcription factors. Overall, these findings demonstrate the involvement of OnPRF in T-cell activation and adaptive immune response in tilapia, thus providing new evidence for comprehending the evolution of immune response in early vertebrates.

Epitope profiling of cow's milk allergen-specific antibodies with determining IgE content in epitopes-ALL, a 14-epitopes mixture

Allergen-specific antibodies (Abs), IgE, and IgG4 increase during the early phase of oral immunotherapy (OIT) of allergen food in patients; subsequently, IgE levels decrease and specific IgG4 levels increase after successful OIT treatment. The detailed profile of these Abs during OIT remains largely unclear. We developed a diagnostic tool to assess the OIT efficacy and extent of responsiveness based on a profiling method by identifying epitopes recognized by the Ab classes of IgE or IgG4.A peptide microarray followed by microplate analysis using synthetic peptides was used to identify 14 epitopes widely recognized by IgE and/or IgG4 in the serum samples of patients with OIT among the amino acid sequences of five major cow's milk allergens. The set of defined 14 epitopes clarified different epitope profiles of allergen-specific IgE and IgG4 in each patient's serum samples. Moreover, the total signal of Abs recognizing all 14 epitopes was equal to the sum of all individual epitope-specific Abs. It was further observed that the quantitative value of IgE concentrations of 14 epitopes-ALL correlated with the ImmunoCAP IgE value.These findings strongly imply that the quantity of IgE and IgG4 recognizing epitopes-ALL may easily be used to measure allergy severity. To investigate this potential, we developed an immunochromatographic method that can detect IgE and IgG4 levels in patient samples.This study clearly demonstrated the usefulness of the defined 14 epitopes and their mixture, “epitopes-ALL,” and that the simple and reliable methods of immunochromatography and microplate analyses demonstrating the epitope profile of allergen-specific Abs are applicable for diagnostic use at multiple disease stages and the OIT-treatment course in patients with cow's milk allergy.

Safety evaluation of the food enzyme α-amylase from the non-genetically modified Bacillus amyloliquefaciens strain AE-BAA.

The food enzyme α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1) is produced with the non-genetically modified microorganism Bacillus amyloliquefaciens strain AE-BAA by Amano Enzyme Inc. The food enzyme is intended to be used in eight food manufacturing processes. Since residual amounts of food enzyme-total organic solids (TOS) are removed in two processes, dietary exposure was calculated only for the remaining six food manufacturing processes. It was estimated to be up to 0.842 mg TOS/kg body weight per day in European populations. The production strain of the food enzyme fulfils the requirements for the qualified presumption of safety (QPS) approach to safety assessment. Consequently, in the absence of other concerns, the Panel considered that toxicological studies were not needed for the safety assessment of this food enzyme. A search for the homology of the amino acid sequence of the food enzyme to known allergens was made and one match with a respiratory allergen was found. Known sources of food allergens were used in the manufacturing process, and the Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the food enzyme glucan-1,4-α-glucosidase from the non-genetically modified Aspergillus niger strain DP-Azh100.

The food enzyme glucan-1,4-α-glucosidase (4-α-d-glucan glucohydrolase; EC 3.2.1.3) is produced with the non-genetically modified Aspergillus niger strain DP-Azh100 by Genencor International B.V. It was considered free from viable cells of the production organism. The food enzyme is intended to be used in four food manufacturing processes. Since residual amounts of total organic solids (TOS) are removed in two processes, dietary exposure was calculated only for the two remaining processes. It was estimated to be up to 1.390 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level at the highest dose tested of 1000 mg TOS/kg bw per day, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 719. A search for the homology of the amino acid sequence of the food enzyme to known allergens was made and one match to a respiratory allergen was found. Known sources of food allergens were used in the food enzyme manufacturing process. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

A dominant missense variant within LMBR1 related to equine polydactyly

Polydactyly was recorded before 100 BCE and attracted widespread interest because of its relationship to limb health and ancestral traits in horses. However, the underlying reasons for the development of polydactyly remain unclear. To search for polydactyly-related genes, we utilize a paternal half-sib family and screen for variants that match the mode of inheritance. Through this screening process, 77 variants in 65 genes are filtered. A missense variant (EqCab3.0 chr4: <107353368> A > G) (rs1138485164) in the 3rd exon of LMBR1 is identified as a source of amino acid sequence variation. Gene editing confirms that the variant down-regulates LMBR1expression, increases the proliferative viability of mutant cells, and inhibits apoptosis. This study suggests that LMBR1 might play a role in the development of polydactyly and that the variant detected in this study is related to polydactyly in horses. However, further research is needed to determine whether a direct relationship exists.

Distinct Effects of SARS-CoV-2 Protein Segments on Structural Stability, Amyloidogenic Potential, and α-Synuclein Aggregation.

Amyloidosis is characterized by the abnormal accumulation of misfolded proteins, called amyloid fibrils, leading to diverse clinical manifestations. Recent studies on the amyloidogenesis of SARS-CoV‑2 protein segments have raised concerns on their potential link to post-infection neurodegeneration, however, the mechanisms remain unclear. Herein, we investigated the structure, stability, and amyloidogenic propensity of a nine-residue segment (SK9) of the SARS-CoV-2 envelope protein and their impact on neuronal protein α-synuclein (αSyn) aggregation. Specifically, the amino acid sequence of the SK9 wildtype has been modified from a basic and positively charged peptide (SFYVYSRVK), to a nearly neutral and more hydrophobic peptide (SAAVASAVK, labelled as SK9 var1), and to an acidic and positively charged peptide (SFYVYSRVK, labelled as SK9 var2). Our findings reveal that the SK9 wildtype exhibited a pronounced amyloidogenic propensity due to its disordered and unstable nature, while the SK9 variants possessed more ordered and stable structures preventing the amyloid formation. Significantly, the SK9 wildtype demonstrated distinct effect on αSyn aggregation kinetics and aggregate morphology to facilitate the formation of αSyn aggregates with enhanced resistance against enzymatic degradation. This study highlights the potential of modifying short peptide sequences to fine-tune their properties, providing insights into understanding and regulating viral-induced amyloid aggregations.

Interferon Regulatory Factors (IRF1, IRF4, IRF5, IRF7 and IRF9) in Sichuan taimen (Hucho bleekeri): Identification and Functional Characterization

Background/Objectives: Interferon regulatory factors (IRFs) are multifunctional transcription factors that play important roles in the transcriptional regulation of interferons and in the immune response to pathogens. Therefore, studying the interferon system in fish is highly relevant in the prevention and treatment of viral diseases. Methods: In this study, five IRF genes (IRF1, IRF4, IRF5, IRF7 and IRF9) were identified and characterized in Hucho bleekeri, and their expression profiles were determined after LPS and Poly(I:C) treatment. Results: These IRFs have typical DNA-binding domains and IRF-association domains. Amino acid sequence comparison revealed high homology between these IRFs and those of other vertebrates, with the highest homology being with other salmonid fish. Phylogenetic analysis revealed that these IRFs are divided into four subfamilies (IRF1, IRF3, IRF4 and IRF5), with both IRF4 and IRF9 belonging to the IRF4 subfamily. IRF genes were widely expressed in all of the tested tissues, with IRF1, IRF4 and IRF9 being highly expressed in the spleen and kidney and IRF5 and IRF7 highly expressed in the gonads. IRF1, IRF4 and IRF5 expression was induced at different time points post-LPS challenge. IRF7 and IRF9 expression in the spleen and head kidney was not significantly altered by LPS induction. Poly(I:C) treatment altered IRF expression more significantly than LPS treatment. Poly(I:C) significantly altered the spleen and head kidney expression of all five IRFs. Conclusions: These findings reveal the potential role of IRFs in the antiviral response of H. bleekeri and provide a reference for examining signal transduction pathways in the interferon system in fish.

Survival Distinctions for Cases Representing Immunologically Cold Tumors via Intrinsic Disorder Assessments for Blood-Sourced TRB Variable Regions.

T cell receptor beta (TRB) sequences were recovered from the Cancer Genome Atlas Uveal Melanoma blood exome files. Intrinsic disorder scores for amino acid (AA) sequences of the entire TRB variable region were obtained and evaluated as potentially representative of overall survival (OS) distinctions, i.e., for cases representing the upper and lower 50th percentiles for intrinsic disorder scores. Analyses using four intrinsic disorder assessment tools indicated that a lower intrinsic disorder of the blood-sourced TRB variable regions, including continuous AA sequences of the V-gene segment, the complementarity-determining region-3, and the J-gene segment, was associated with a better OS probability (with log-rank p-values ranging from 0.002 to 0.014). We further determined that intrinsic disorder assessments could be used for OS stratification for a second, immunologically cold cancer: MYCN amplified neuroblastoma. Thus, intrinsic disorder assessments of blood-sourced, full TRB variable regions may provide a novel patient stratification approach for patients with immunologically cold cancers.

Intrinsic Natural Resistance of Various Plant Pathogens to Ipflufenoquin, a New DHODH (Dihydroorotate Dehydrogenase)-inhibiting Fungicide, in Relation to Unaltered Amino Acid Sequence of the Target Site.

In recent years, increasingly stringent pesticide regulations have made the development of new chemistries challenging. Under these regulations, the new fungicide ipflufenoquin (FRAC Code 52) was first released in Japan. Its mode of action is new; it inhibits dihydroorotate dehydrogenase (DHODH), a key enzyme in the biosynthesis of pyrimidine-based nucleotides. However, because it is a single-site inhibitor, the risk of resistance developing in pathogens must be carefully considered. The risk for dual use of DHODH inhibitors in agriculture and medicine has also become a great concern because a new antifungal olorofim is under development against human pathogens now and cross-resistance has recently been reported between ipflufenoquin and olorofim in Aspergillus fumigatus. In this study, the sensitivity to ipflufenoquin was examined in culture and in plants using "baseline" isolates, which had never been exposed to DHODH inhibitors. Isolates of Alternaria alternata, Botrytis cinerea, B. elliptica, Colletotrichum fioriniae, C. fructicola, C. nymphaeae, C. orbiculare, C. siamense, C. tropicale, C. truncatum, and Sclerotinia sclerotiorum were highly sensitive to ipflufenoquin in culture, but isolates of Coniella vitis, Corynespora cassiicola, Pseudocercospora fuligena, and Rhizoctonia solani were inherently resistant. Ipflufenoquin had low efficacy against C. cassiicola and C. vitis after inoculation of cucumber and grapevine leaves, respectively. To understand the mechanism of natural resistance, we analyzed the partial sequence of pyrE genes, which encode the DHODH enzyme, but did not find any differences in the deduced amino acids that were thought to be associated with resistance. Thus, mechanisms other than target-site mutations might be involved in the intrinsic resistance.

AlphaFold Meets De Novo Drug Design: Leveraging Structural Protein Information in Multitarget Molecular Generative Models.

Recent advancements in deep learning and generative models have significantly expanded the applications of virtual screening for drug-like compounds. Here, we introduce a multitarget transformer model, PCMol, that leverages the latent protein embeddings derived from AlphaFold2 as a means of conditioning a de novo generative model on different targets. Incorporating rich protein representations allows the model to capture their structural relationships, enabling the chemical space interpolation of active compounds and target-side generalization to new proteins based on embedding similarities. In this work, we benchmark against other existing target-conditioned transformer models to illustrate the validity of using AlphaFold protein representations over raw amino acid sequences. We show that low-dimensional projections of these protein embeddings cluster appropriately based on target families and that model performance declines when these representations are intentionally corrupted. We also show that the PCMol model generates diverse, potentially active molecules for a wide array of proteins, including those with sparse ligand bioactivity data. The generated compounds display higher similarity known active ligands of held-out targets and have comparable molecular docking scores while maintaining novelty. Additionally, we demonstrate the important role of data augmentation in bolstering the performance of generative models in low-data regimes. Software package and AlphaFold protein embeddings are freely available at https://github.com/CDDLeiden/PCMol.

In-silico immunoinformatic vaccine design for Treponema denticola ergothionase.

Treponema denticola, a well-studied oral spirochete, adheres, invades, and damages periodontal tissues - gram-negative, anaerobic Treponema denticola. In previous research, sub-gingival spirochetes have correlated positively with dental plaque score, pocket, and clinical attachment level measurements. Hence, the study aims to design an immunoinformatic vaccine using a reverse vaccinology approach against Treponema denticola ergothionase. Protein Data Bank provided the FASTA amino acid sequence of Treponema denticola. Antigenicity, toxicity, and stability of discovered T-cell epitopes were evaluated to develop 6S7Q B and A multiepitope vaccination design. The Vaccine's dual major histocompatibility complex (MHC I and II) binding epitopes were also predicted. The designed Vaccine's identified epitope sequence and secondary structure were then predicted and validated. Protein-protein interactions involving ergothionase and human beta-defensins were investigated using molecular docking. The designed Vaccine had high antigenicity, toxicity, and stability. The Vaccine's three-dimensional structure demonstrated a significant association with beta-defensin. Its low binding energy score of -827.6 kcal/mol indicates that the immune system will respond favorably to the antigen. In this research, we employed immunoinformatic techniques to create a reverse vaccination effort to develop an in-silico vaccine.

Molecular approach to the characterization of lipase encoding genes from Moraxella sp. SBE01

Lipase from Moraxella sp. SBE01 is an expression of the gene encoding lipase. Detection and characterization of the Moraxella sp. SBE01 lipase coding gene is necessary for large-scale lipase production through genetic engineering. This study aimed to observe the molecular weight, amino acid sequence, length, and conserved amino acids in the DNA encoding the lipase gene, with the goal of identifying and characterizing the lipase-coding gene from Moraxella sp. SBE01. The primer design process was conducted to amplify the lipase gene from Moraxella sp. SBE01 using specialized software for sequence alignment and phylogenetic analysis. Amplification was carried out using PCR with the designed primer, forward primer (GTC ATG ATG TAC TTC CAY GGN GGN GG), reverse primer (GGT TGC CGC CGG CDS WRT CNC C). PCR was carried out under pre-denatured conditions at 95°C (3 minutes), followed by 30 cycles of denaturation at 95°C, annealing at 66°C (30 seconds), 70°C elongations (1 minute) and final elongation of 70°C (10 minutes). The PCR results were electrophoresed using 1% agarose gel with a 1 kb DNA marker. The PCR results were sequenced and analyzed for gene and amino acid sequences and the type of lipase expressed. Sequencing resulted in 387 bp of the nucleotide sequence. The gene and amino acid sequences from Moraxella sp. SBE01 had high homology with the gene and amino acid sequences from Moraxella sp. strain TA144. The lipase gene encodes a protein consisting of 129 amino acids and contains a conserved HGG (His-Gly-Gly) motif, which is characteristic of lipases in family IV, also known as the hormone-sensitive lipase (HSL) family. This conserved sequence suggests that the lipase shares structural and functional similarities with other enzymes in the HSL family, playing a key role in lipid metabolism.

The Yeast Ribosomal Protein Rpl1b Is Not Required for Respiration.

Previously, Segev and Gerst found that mutants in any of the four ribosomal protein genes rpl1b, rpl2b, rps11a, or rps26b had a petite phenotype-i.e., the mutants were deficient in respiration. Strikingly, mutants of their paralogs rpl1a, rpl2a, rps11b, and rps26a were grande-i.e., competent for respiration. It is remarkable that these paralogs should have opposite phenotypes, because three of the paralog pairs (Rpl1a/Rpl1b, Rpl2a/Rpl2b, Rps11a/Rps11b) are 100% identical to each other in terms of their amino acid sequences, while Rps26a and Rps26b differ in 2 amino acids out of 119. However, while attempting to use this paralog-specific petite phenotype in an unrelated experiment, I found that the rpl1b, rpl2b, rps11a, and rps26b deletion mutants are competent for respiration, contrary to the findings of Segev and Gerst.

Hybrid Metal Catalysts as Valuable Tools in Organic Synthesis: An Overview of the Recent Advances in Asymmetric C─C Bond Formation Reactions.

Carbon-carbon bond formation represents a key reaction in organic synthesis, resulting in paramount importance for constructing the carbon backbone of organic molecules. However, traditional metal-based catalysis, despite its advantages, often struggles with issues related to efficiency, selectivity, and sustainability. On the other hand, while biocatalysis offers superior selectivity due to an extraordinary recognition process of the substrate, the scope of its applicable reactions remains somewhat limited. In this context, Artificial Metalloenzymes (ArMs) and Metallo Peptides (MPs) offer a promising and not fully explored solution, merging the two fields of transition metal catalysis and biotransformations, by inserting a catalytically active metal cofactor into a customizable protein scaffold or coordinating the metal ion directly to a short and tunable amino acid (Aa) sequence, respectively. As a result, these hybrid catalysts have gained attention as valuable tools for challenging catalytic transformations, providing systems with new-to-nature properties in organic synthesis. This review offers an overview of recent advances in the development of ArMs and MPs, focusing on their application in the asymmetric carbon-carbon bond-forming reactions, such as carbene insertion, Michael additions, Friedel-Crafts and cross-coupling reactions, and cyclopropanation, underscoring the versatility of these systems in synthesizing biologically relevant compounds.

Structural Insights into the Iodothyronine Deiodinase 2 Catalytic Core and Deiodinase Catalysis and Dimerization

Iodothyronine deiodinases (Dio) are selenocysteine-containing membrane enzymes that activate and inactivate the thyroid hormones (TH) through reductive iodide eliminations. The three deiodinase isoforms are homodimers sharing highly conserved amino acid sequences, but they differ in their regioselectivities for the deiodination reaction and regulatory features. We have now solved a crystal structure of the mouse deiodinase 2 (Dio2) catalytic domain. It reveals a high overall similarity to the deiodinase 3 structure, supporting the proposed common mechanism, but also Dio2-specific features, likely mediating its unique properties. Activity studies with an artificially enforced Dio dimer further confirm that dimerization is required for activity and requires both the catalytic core and the enzyme’s N-terminus. Cross-linking studies reveal the catalytic core’s dimerization interface, providing insights into the architecture of the complete, active Dio homodimer.