Biochimie

Sulfation plays an important role in many metabolic processes such as substrate detoxification, solubilization or activation. The enzymes responsible for these reactions, sulfotransferases, occur in all domains of life and can be classified in two major, evolutionary independent groups, PAPS dependent and PAPS independent or arysulfate sulfotransferases (ASST) enzymes. Besides the fact that they play key roles in biological functions, sulfotransferases can be interesting enzymatic tools to selectively sulfate specific positions of various metabolites. To this end we need to understand the relation between sequence, structure and function. Actually, eukaryotic PAPS dependent sulfotransferases have extensively been studied, while we largely lack knowledge about the diversity of bacterial PAPS-independent ASSTs. We have conducted a multidisciplinary study of a bacterial sulfotransferase from Salmonella typhimurium, revealing the importance of active site residues for activity and guiding substrate specificity. Based on the crystal structure in complex with substrate, we used molecular docking combined with Quantum Mechanics/Molecular Mechanics (QM/MM) free energy calculations to investigate the reaction catalytic mechanism with a focus on the role of specific active site residues in substrate specificity. Our results show that the catalytic mechanism involving three conserved histidines is common with previously determined ASSTs, and highlight a specific pair of aromatic residues, Phe174 and Tyr557, that play an important role in defining the substrate specificity in ASST clade 5. These findings enhance our general understanding of how substrate specificity is attained and has the potential to guide further enzyme engineering to expand the acceptor scope of ASSTs.

Thrombostasin is a cysteine-free anticoagulant protein produced by the horn fly Haematobia irritans, featuring an unusual stretch of seven consecutive aspartate residues within the polypeptide sequence. Here, we report the first chemical synthesis of native thrombostasin and a hepta-glutamate analogue, together with assessment of their thrombin inhibitory and anticoagulant activity.

Human Ca2+/calmodulin (CaM)-dependent protein kinase II alpha (CaMKII) is a highly abundant and conserved protein in the brain. It is a multifunctional serine/threonine kinase that phosphorylates cellular substrates across subcellular compartments, activating signaling pathways essential for long-term memory storage. However, a detailed understanding of protein structure and enzyme-substrate interaction mechanisms require a method to produce active, stable, and pure proteins at scale. Since phosphorylation can alter catalytic activity and substrate affinity, examining the non-phosphorylated state enables an unbiased characterization of basal enzymatic function. Therefore, producing the non-phosphorylated form of the kinase is important for biochemical and structural studies aimed at understanding kinase activation mechanisms. We describe a detailed protocol for the expression and high-yield purification of full-length, non-phosphorylated human CaMKII in bacterial cells. CaMKII was co-expressed with {lambda}-phosphatase to maintain it in a non-phosphorylated state. Protein expression was induced by autoinduction at low temperature to enhance the stability and solubility of CaMKII. Recombinant CaMKII was purified by Ni-NTA affinity chromatography, followed by gel filtration chromatography. Although CaMKII has been considered difficult to purify in its non-phosphorylated form, we obtained it in high yield, and the protein was predominantly non-phosphorylated. Our results show that combining co-expression with autoinduction improves both the solubility and yield of the homogeneous non-phosphorylated form of CaMKII, which could be suitable for subsequent biochemical and structural studies.

G protein-coupled receptors (GPCRs) represent the largest membrane protein family in the human body and the major targets of FDA-approved medications. Unlike some other physiological proteins, GPCRs are highly plastic and often exist as collections of conformational ensembles in the environment to exert their function. Therefore, understanding how a GPCR adopts different conformational ensembles in response to ligands and signaling partners is essential for drug development. 19F-NMR has emerged as one of the most promising tools in this regard; however, a well-established 19F-labeling system is still lacking, including an effective 19F probe that meets both environmental susceptibility and NMR sensitivity requirements, even though progress has been made dramatically in recent years. Thus, this manuscript reports a novel conformational probe (4-(bromomethyl)-ethoxy-2-(trifluoromethyl)benzene, BTMB) that offers paramount benefits for future GPCR conformational dynamics studies. To rationalize the mechanism behind BTMB's superiority for future probe development, we performed MD simulations, referenced to the current state-of-the-art probe, BTFMA. Our study suggests that the spatial proximity of aromatic residues significantly influences the chemical shift dispersion and linewidths of related 19F-probe-profiled conformational states, as well as the rigidity and compactness of -CF3 in the target protein.

Alkaline ceramidase 2 (ACER2) catalyzes the hydrolysis of ceramides into sphingosine and free fatty acids, playing crucial roles in regulating various biological processes, including but not limited to cell proliferation, survival, and the DNA damage response. However, a pharmacological tool that regulates its catalytic and signaling functions remains to be developed. In this study, N-[(1S,2R)-1-hydroxy-1-phenylpropan-2-yl]dodecane-1-sulfonamide (KPB82) was identified as a potent and selective ACER2 inhibitor. In vitro enzymatic assays showed that KPB82 inhibited ACER2 with an IC50 of 190 nM, while displaying minimal activity against acid and neutral ceramidases (IC50> 100 {micro}M) and no significant inhibition of alkaline ceramidase 1 or alkaline ceramidase 3. Enzymatic kinetic studies revealed that KPB82 is a competitive inhibitor of ACER2. The three-dimensional structure of ACER2 was modeled in the AlphaFold3 server, revealing key Zn2+-coordinating histidine residues and a substrate-binding pocket. Molecular docking studies demonstrated that KPB82 binds ACER2 within this pocket, forming hydrogen bonds with the catalytically important amino residues, Asp93 and His215, and interacting with several hydrophobic residues. Lactate dehydrogenase release assays revealed that KPB82 significantly reduced cytotoxicity in HeLa cells overexpressing ACER2, as well as in HCT116 cells, RT4 cells, and human umbilical vein endothelial cells treated with the DNA-damaging agent doxorubicin. Lipidomic analysis showed that KPB82 inhibited sphingosine production in response to ACER2 overexpression or doxorubicin treatment. Collectively, these findings demonstrate that KPB82 is a potent and selective ACER2 inhibitor capable of suppressing ACER2-dependent biological processes and highlight its potential as a tool for studying ceramide metabolism and ACER2-mediated signaling pathways.

Protein degradation mediated by PROteolysis TArgeting Chimeras (PROTACs) is a complex, dynamic, and multi-step process. The structural diversity of PROTACs, coupled with cellular heterogeneity, introduces considerable variability at each stage. Therefore, a straightforward yet comprehensive approach is essential to effectively dissect these mechanisms. The existing methods for evaluating PROTAC degradation are often time-consuming, labor-intensive, or expensive, and many capture only a partial view of the entire degradation process. Consequently, multiple complementary assays are typically required to obtain the complete picture. Here, we use commercially available Cyclin dependent Kinase 6 (CDK6) targeting PROTACs to demonstrate that a simple, single-step, no-wash, additive-free, GFP-based live-cell imaging approach can rapidly generate dynamic degradation metrics (Dmax, Rmax, TDmax, CDmax, DC50, Km, Tmax, Kdeg, Vmax, DT50, {tau} and TRmax) for comparing and ranking PROTACs within a controlled reporter system. The rapid assay turnaround time, excellent assay qualities and compatibility with high-throughput (HT) formats will facilitate quick hit identification and serve as a guiding assay for hit-to-lead optimization campaigns.

Introduction: In both humans and experimental animals, obesity is associated with hypothalamic inflammation and neuronal metabolic dysfunction, which contribute to disrupting body energy homeostasis. Although ciliary neurotrophic factor (CNTF) is a neuroprotective cytokine with recognized anti-obesity effects in peripheral metabolic tissues, its role in obesity-associated hypothalamic dysfunction is still poorly characterized. We investigated whether CNTF exerts any direct effects on mHypoE-N41 (N41) hypothalamic neurons and whether it modulates the effects induced by palmitate (PA), an established model of obesity-associated neuronal metabolic dysfunction. Methods: N41 cells were administered CNTF alone or combined with PA to assess whether CNTF affects PA-induced lipotoxic stress. Gene and protein expression was assessed by qRT-PCR, western blotting, and immunofluorescence analysis. Results: In N41 cells, CNTF activated the STAT3, ERK and AMPK signaling pathways. It also upregulated genes involved in mitochondrial metabolism and fatty acid oxidation, including Ucp2, Cpt1 and Pgc1, as well as the proliferation-associated markers Ki-67 and PCNA. PA treatment induced inflammatory and endoplasmic reticulum stress responses and impaired insulin signaling. In PA-treated N41 cells, CNTF significantly attenuated the expression of pro-inflammatory markers Tnf, Mcp1 and Nfkb, restored insulin-induced AKT phosphorylation, and partially reversed PA-induced changes in the expression of metabolic genes Ucp2 and Cpt1. Conclusions: Collectively, these findings indicate that CNTF exerts direct protective metabolic effects on hypothalamic N41 neurons subjected to lipotoxic stress and supports a role for it in the preservation of neuronal metabolic function under obesogenic conditions.

The enzymatic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a key step in the sustainable production of polyethylene furanoate (PEF), yet the final oxidation of 5-formyl-2-furancarboxylic acid (FFCA) to FDCA remains the principal bottleneck for industrial application. Although hydroxymethylfurfural oxidases (HMFOs) can catalyze this transformation, naturally occurring enzymes with high FFCA-oxidizing activity remain largely unexplored. Here, we present an iterative computational bioprospecting campaign to identify natural HMFOs with improved activity toward this rate-limiting reaction. Across four successive rounds, the computational workflow evolved from conservative homology-based screening to large-scale sequence mining assisted by machine learning, with each iteration redesigned according to the principal limitations identified through molecular simulations and experimental characterization. This adaptive strategy led to the discovery of several natural HMFOs with substantially improved FFCA oxidation activity, including candidates whose performance under the tested conditions approached that of the engineered benchmark 8BxHMFO. Beyond the identification of promising biocatalysts, the study demonstrates the value of continuous integration of computational prediction and experimental feedback for refining enzyme discovery campaigns, and provides practical insights into balancing catalytic prioritization, sequence diversity, developability, and computational scalability in future simulation-guided bioprospecting efforts.

RNA interference (RNAi) offers a sequence-specific approach to pest control. In insects, Dicer-2 processes double-stranded RNA (dsRNA) into small interfering RNA (siRNA) duplexes, from which the RNA-induced silencing complex (RISC) retains a guide strand. Only antisense-loaded RISC can mediate cleavage of the target transcript. However, how sequence features shape the RISC-bound siRNA pool in pests remains poorly understood, limiting opportunities for sequence optimization. Here, we profiled RISC-bound siRNAs following injection of 34 insecticidal dsRNAs targeting 11 essential genes in Tribolium castaneum larvae. We computationally reconstructed 7,879 siRNA pairs and examined associations between sequence features and strand bias. Differences in GC identity at terminal paired positions 1 to 5, used as a proxy for local thermodynamic asymmetry, correlated with strand bias, with the strongest correlations at the first two paired positions. ORF targeting and reduced predicted antisense self-folding were also associated with higher antisense fractions. Analysis of non-templated terminal additions revealed predominantly 3-prime uridylation, a known signature of small RNA turnover, along with putative 3-prime trimming. Among ORF-associated siRNA pairs, sense strands showed higher relative U-tailing abundance, based on 3-prime uridylated and putatively trimmed-and-3-prime-uridylated reads relative to perfect 21-nt reads, than antisense strands. Antisense strands with the least predicted self-folding also showed low relative U-tailing abundance. These observations are consistent with sequence-dependent contributions from both guide-strand selection and differential post-RISC-loading siRNA retention, although a causal link remains to be established. The identified associations provide a basis for testing whether dsRNA sequence optimization can improve pest control efficacy and reduce off-target activity.

Vertical transmission of SARS-CoV-2 is controversial. Owing to the low expression of ACE2 along with TMPRSS2 in placenta, role of secondary receptors becomes significant. In our study we predicted twelve interactors of spike protein expressed in placenta through interactome analysis followed by docking and molecular dynamic simulation. Three interactors of SARS-CoV-2 spike protein were found to be CD147, EGFR and LDLR. Expression at transcriptomic and translational level by real-time PCR and immunohistochemistry respectively was observed in placenta samples obtained from women with COVID exposure risk and compared to control. Elevated protein levels of CD147 (OR=14.667), ACE2 (OR=8.25) and LDLR (OR=1.9) was associated with higher exposure risk. However, the variation in mRNA expression was not statistically significant. Computational study showed that CD147/basigin, EGFR and LDLR stably interact with spike protein outside its primary receptor binding domain. In-vitro binding assay confirmed the physical interaction between spike protein and the placental receptors. In-silico site-directed mutagenesis further identified key potential binding hotspots of spike protein- Tyr28 and Trp64 for CD147, Phe643, Val642, Thr632 for LDLR and Leu8, Phe59, Phe32, Tyr28, Trp64, Trwp152, His245, and Val213 for EGFR. Finally, concluded that CD147, EGFR and LDLR might act as secondary non-canonical cofactors for SARS-CoV-2 spike protein in placenta, thereby increasing its susceptibility and tissue tropism. The study overall gives a better insight into potential placental suscpetibility providing targeted therapeutic opportunities.

Glycine transporter 1 (GlyT1) is a clinically investigated target whose conformational plasticity enables ligands to engage distinct extracellular and intracellular binding sites. However, methods to directly quantify intracellular binding remain limited and largely rely on radioligand-based approaches. Here, we report a NanoBRET-based binding assay to quantify intracellular GlyT1 target engagement in living cells using a fluorescent tracer derived from the GlyT1 inhibitor Cmpd1. With a structure-based approach followed by pharmacological characterization we identified a suitable meta-substituted exit vector for linker and fluorophore attachment while maintaining GlyT1 binding. A series of fluorescent probes was synthesized and evaluated, leading to the development of GlyT1-probe which displayed high-affinity binding and enabled robust NanoBRET measurements. Unlike the functional uptake assay, the NanoBRET assay distinguished intracellular from extracellular GlyT1 inhibitors and resolved structure-activity relationships at the intracellular binding site. This assay provides a quantitative approach to interrogate conformation-selective GlyT1 target engagement in living cells, facilitating the characterization of GlyT1 ligands targeting the intracellular site.

Carbohydrates are essential molecules involved in a wide range of biological processes. While their structural representation in the Protein Data Bank (PDB) has been hindered due to their highly diverse and flexible nature, advancements on X-ray crystallography and CryoEM are accelerating the obtaining of their experimental structures, which in turn supports improved analyses of their structural properties, such as the role of their non-chair conformations on biological processes. In this context, the current work provides a comprehensive and up to date overview of carbohydrate structures within the PDB through classification, quantification, and characterization of monosaccharides and glycan chains, incorporating Cremer-Pople puckering coordinates to evaluate pyranose conformations. Our findings show that, even with a steep increase in CryoEM structures including more complex oligosaccharides, carbohydrate data remains concentrate dinsmallglycanchains, with a about 4% of non-chair conformation sintopresolution structures. Free energy landscapes for the pyranose ring in the presence and absence of nine different binding proteins, including both enzymes and non-enzymes, reinforce the preferred stability of chairs and the rarity of conformational induction upon binding.

In eukaryotic cells, the positive transcription elongation factor b (P-TEFb) plays a critical role in the transition of RNAPII from the paused state to actively transcribing mode. Although three different cyclin (Cyc) T (CycT1, T2a, and T2b) interact with CDK9 to form functional P-TEFb, a majority of P-TEFb complexes are comprised of the CycT1 and CDK9. To analyze the role of the CycT1 subunit of P-TEFb on cellular transcription, we established HEK293T cells lacking CycT1 proteins (CycT1-KO cells). While no apparent growth defects were observed with CYcT1-KO cells, the level of CDK9 was decreased and no compensatory over-expression of CycT2 was observed, suggesting that the reduced level of functional P-TEFb complexes is sufficient for the normal cell growth. Reporter gene assays indicate that NF-kappaB-dependent transcription induced by PMA was impaired in CycT1-KO cells although the function of NF-kappaB (P65) per se was not affected. On the other hand, AP1-dependent transactivation induced by PMA was unaffected in CycT1-KO cells. Moreover, transcription stimulated by JQ1, a strong P-TEFb inducer, was reduced in CycT1-KO cells. Data of biochemical analysis indicate that P-TEFb with CycT1 (P-TEFb (CDK9:CycT1)) was efficiently released from 7SKsnRNP by JQ1 while P-TEFb (CDK9:CycT2) was not affected by JQ1. Transcriptome analysis indicated that the lack of CycT1 had a minor effect on the steady-state transcription. However, expression of JQ1-dependent genes was severely reduced in CycT1-KO cells. Interestingly, referring to gene expression profiles of 33 different types of cancer revealed that 11 out of 13 top JQ1-dependent genes were also highly upregulated in Pancreatic Adenocarcinoma. From these results, we conclude that although many genes can be regulated by both P-TEFb (CDK9:CycT1) and P-TEFb (CDK9:CycT2), CycT1 plays a critical role in regulating highly inducible genes, which are also aberrantly regulated in a particular type of cancer.

A challenge in synthetic biology is to transfer the knowledge acquired in vitro to in vivo applications. For instance, binding affinity between peptide binding domains (PBDs) and their binding peptides is usually measured in simple buffers and in the absence of the cell machinery responsible for synthesis and proteostasis. Consequently, there is often a discrepancy between interaction quantified in vitro and in vivo. To identify strongly binding PBD-peptide pairs for in vivo applications, we aim to better understand the determinants of synthetic interaction in living yeast cells. We designed libraries of peptides expected to bind to PBDs based on data collected by phage-display. Using an in vivo protein interaction assay, we assessed the interaction strength of >6,500 PBD-peptide variants in yeast. We found that most substitutions disrupt binding, but that 3.4% increased binding strength to levels higher than expected from the phage-display data. We asked if, by using our mutational data, it was possible to optimize peptide sequences to gain even more binding strength and show additivity effect up to four substitutions. We found that PBD specificity is consistent between in vitro and in vivo assays. We hypothesized that in vivo peptide abundance could contribute to the discrepancy between the PCA and the phage-display results. We performed assays to detect in vivo peptide availability, reporting on peptide abundance, and we found that peptides with a stronger binding also show a higher availability in cells. We show that peptide availability, which seems mainly defined by peptide hydrophobicity, is key for the design of strong synthetic interactions.

Background: Endometriosis is an estrogen-driven, inflammatory disorder affecting ~10% of menstruators, causing severe pain. Current treatments that reduce estrogen or inflammation have inconsistent efficacy and poor tolerability. Therapies identified via drug-repositioning methods, which target patient-specific pathways, offer a promising alternative. Simvastatin and primaquine were identified as potential treatments, strongly reversing endometriosis-associated gene expression pathways, and behavioral testing in an animal model showed that these drugs diminish endometriosis-associated pain. This paper examines their effects in human assembloids to provide proof-of-concept validation and insights into their mechanisms of action relevant to endometriosis. Methods: We established human endometrial assembloids using immortalized epithelial (12Z) and stromal fibroblast (iEc) cell lines, as well as primary tissue from patients. Assembloids were generated in 96-well agarose molds with both cell types. We tested ibuprofen, fenoprofen, primaquine, and simvastatin. Following a 24-hour exposure, assembloids and monolayer cultures were harvested and stranded mRNA-seq libraries were sequenced on an Illumina NovaSeqX Plus System. Results: Gene set enrichment analysis showed key pathway reversals: Primaquine reversed the chemical carcinogenesis ROS pathway in assembloids. Simvastatin reversed cytokine-cytokine receptor interaction in both epithelial and stromal cell lines, and the cytoskeleton in muscle cells pathway in stromal cell lines. Fenoprofen reversed the calcium signaling pathway in stromal cell lines. Conclusion: Simvastatin induced the most significant gene expression changes, notably reversing cytokine-cytokine receptor interactions in both cell lines, mirroring findings from our rat model. Despite the small sample size limitation, these experiments highlight the promise of assembloid models to test therapeutic candidates for endometriosis.

Polyhydroxyalkanoates (PHAs) are microbial polyesters that represent a sustainable alternative to fossil fuel-based plastics. These biodegradable polymers have properties similar to conventional plastics and can be produced from waste materials. The key enzyme in PHA synthesis is PHA synthase (PhaC) and despite its importance, only a few PhaCs from extremophilic microorganisms have been characterised in detail. Here we characterised PHA synthase enzyme from the thermophilic bacterium Caldimonas thermodepolymerans DSM15344, an attractive candidate for PHA production from lignocellulosic residues due to its unique properties such as utilisation of xylose-rich substrates and high PHA yields on this pentose sugar. PhaC was successfully expressed in the surrogate host E. coli BL21 (DE3) GOLD, purified to homogeneity and its enzymatic activity was confirmed in vitro. The optimal pH range and temperature were determined as 6.3-6.9 and 50 {degrees}C, respectively. The melting temperature of PhaC was detected at 57.83 {+/-} 0.04 {degrees}C and the enzyme storage stability was assessed. The tertiary structure, including the enzyme active site, was predicted using available bioinformatic tools and the predicted catalytic residues were supported by site-directed mutagenesis. This study represents the first biochemical characterisation of PHA synthase from C. thermodepolymerans, expanding the limited set of characterised thermophilic PhaC enzymes.

Background: Long non protein coding (lnc)RNAs are ubiquitous transcripts known to be major regulators of cellular processes in eukaryotes. In diatoms, specific lncRNA expression is tightly correlated to nutrient fluctuations, which suggests function, but their biological relevance remains to be established. In order to fill this knowledge gap, we sought to design a protocol to generate diatom lncRNA knockout mutants by CRISPR-Cas9 enabling subsequent functional studies to shed light into their mechanistic roles. Since lncRNAs do not contain open reading frames that can be targeted by point mutations for the generation of functional knockouts, we designed a multiplexed CRISPR-Cas9 plasmid harboring two independent gRNA for the specific ablation of lncRNA loci in P. tricornutum. As proof of concept, we used our plasmid-based system to target three phosphate depletion responsive lncRNAs. Results: Using the golden gate based uLoop system, we assembled a single plasmid containing all the necessary components to generate CRISPR-Cas9 large genomic ablations of lncRNAs in P. tricornutum using bacterial conjugation. Three intergenic lncRNAs (Linc91, Linc77 and Linc24) responsive to phosphate fluctuations were selected and independently targeted. Around 32% of the exconjugants presented a monoallelic ablation of the targeted loci and 11% presented a biallelic ablation on the first PCR-screening round. Mutated lines, harboring biallelic lncRNAs ablations for each lncRNA targeted, were successfully generated for each of the targeted lncRNAs. Additionally, a first line of phenotypic analysis revealed significant growth rate differences for one of the mutants ({Delta}Lnc24) under both full and phosphate depleted conditions, suggesting its involvement in cell division regulation under nutrient fluctuations. Conclusions: This work provides a simple and efficient method for the generation of lncRNA knock-out mutants in P. tricornutum. Furthermore, this approach can be easily adapted to other microalgae amenable to transformation, enabling the enhancement of our understanding of these important cellular regulatory transcripts in the marine environment.

The dopamine D2 receptor is a principal target of antipsychotic and antiparkinsonian drugs, yet well-characterized fluorescent ligands for the D2 receptor remain scarce compared with its relative, the D3 receptor. Here we show that fluorescent ligands developed for the D3 subtype can be repurposed as tools for studying the D2 receptor pharmacology. Using a machine-learning-assisted, live-cell fluorescence microscopy assay, we screened twelve fluorescent probes and identified eight ligands that bound specifically to the D2 receptor at 10 nM. Four ligands exhibited classical saturable binding, yielding Kd in the nanomolar range, whereas the remaining probes displayed unsaturated, time-dependent binding profiles. Kinetic analyses revealed substantial differences in association and dissociation behavior, highlighting the importance of time-resolved measurements. Competition binding with dopamine and haloperidol yielded affinity estimates consistent with literature values. These results expand the toolkit of validated D2 receptor fluorescent probes and support cross-receptor repurposing as a strategy for fluorescent ligand development.

Progesterone governs the establishment and maintenance of pregnancy in ruminants, acting through the nuclear progesterone receptor (PGR) and, potentially, through membrane progesterone receptors (mPRs) of the PAQR family. The cellular distribution of mPRs in ruminant reproductive tissues, however, remains undefined. We generated and validated rabbit polyclonal antibodies against the intracellular C-terminal peptides of bovine PAQR6 (mPR{delta}) and PAQR8 (mPR{beta}), and used them, with quantitative PCR of the uterus and conceptus, to map these receptors in the ovine uterus and conceptus and in the bovine ovary. Both antisera showed high ELISA titer against their immunizing peptides, negligible preimmune reactivity, and complete loss of tissue signal after peptide pre-absorption. By qPCR, PAQR6, PAQR8 and PGR transcript levels did not change significantly across the peri-implantation period in either the conceptus or the endometrium; in contrast, the progesterone-responsive gene ZBTB16 increased markedly in the conceptus (up to ~45-fold by day 21, p < 0.05 at days 17, 19 and 21), whereas FKBP5 showed a numerical increase without reaching statistical significance. Both genes remained relatively stable in the endometrium, indicating conceptus-specific changes in progesterone-responsive gene expression. At the protein level, PAQR6 and PAQR8 localized to the luminal and glandular epithelium of the endometrium across the cycle and early pregnancy, and to follicular (granulosa) and luteal cells of the ovary. Dual immunofluorescence in the ovine endometrium showed that both PAQR6 and PAQR8 are enriched at the apical surface of the luminal epithelium and are spatially distinct from the basolateral adherens-junction marker E-cadherin. These results provide a protein-level map of PAQR6 and PAQR8 in the ruminant reproductive tract, identify the apical epithelial surface as a site of receptor enrichment, and show that the endometrial epithelium retains membrane progesterone receptors while progesterone-responsive gene expression changes dynamically in the conceptus during the peri-implantation period. The validated ruminant-reactive antibodies provide a resource for future functional studies.

This study aims to identify potential inhibitors of the Ag85C enzyme from Mycobacterium tuberculosis through primary docking, pharmacophore modelling, and ADME/pharmacokinetics analysis. Delamanid and Pretomanid emerged as the top hits in primary docking, demonstrating strong binding affinities and interactions with key active site residues. A robust pharmacophore model was developed, identifying essential features for binding and used to screen 4254 antituberculotic compounds, yielding three promising candidates: F0314-0040, F0398-0505, and F0349-2716. These compounds exhibited high binding affinities in major docking studies. ADME and pharmacokinetics analysis revealed favorable Drug likeness and absorption profiles, supporting their potential as effective antituberculotic agents. The integration of computational methods provided a comprehensive approach for rational drug design.