A dew-responsive pectin-based herbicide for enhanced photodynamic inactivation.

5-aminolevulinic acid (5-ALA) has been fully demonstrated as a biodegradable, without resistance, and pollution-free pesticide. However, the lack of targeting and the poor adhesion result in a low utilization rate, limiting its practical application. Herein, a dew-responsive polymer pro-pesticide Pec-hyd-ALA was successfully synthesized by grafting 5-ALA onto the pectin (PEC) backbone via acid-sensitive acylhydrazone bonds. When the pro-pesticide is exposed to acid dew on plant surfaces at night, 5-ALA is released and subsequently converted to photosensitize (Protoporphyrin IX, PpIX)in plant cells, leading to its accumulation and promoting photodynamic inactivation (PDI). An inverted fluorescence microscope has verified the accumulation of tetrapyrrole in plant cells. In addition, the highly bio-adhesive PEC backbone effectively improved the wetting and retention of 5-ALA on leaves. The pot experiment also demonstrated the system's control effect on barnyard grass. This work provides a promising approach to improving the herbicidal efficacy of 5-ALA.

Flexible scaffold-based cheminformatics approach for polypharmacological drug design.

Effective treatments for complex central nervous system (CNS) disorders require drugs with polypharmacology and multifunctionality, yet designing such drugs remains a challenge. Here, we present a flexible scaffold-based cheminformatics approach (FSCA) for the rational design of polypharmacological drugs. FSCA involves fitting a flexible scaffold to different receptors using different binding poses, as exemplified by IHCH-7179, which adopted a "bending-down" binding pose at 5-HT2AR to act as an antagonist and a "stretching-up" binding pose at 5-HT1AR to function as an agonist. IHCH-7179 demonstrated promising results in alleviating cognitive deficits and psychoactive symptoms in mice by blocking 5-HT2AR for psychoactive symptoms and activating 5-HT1AR to alleviate cognitive deficits. By analyzing aminergic receptor structures, we identified two featured motifs, the "agonist filter" and "conformation shaper," which determine ligand binding pose and predict activity at aminergic receptors. With these motifs, FSCA can be applied to the design of polypharmacological ligands at other receptors.

Recognition of methamphetamine and other amines by trace amine receptor TAAR1.

Trace amine-associated receptor 1 (TAAR1), the founding member of a nine-member family of trace amine receptors, is responsible for recognizing a range of biogenic amines in the brain, including the endogenous ß-phenylethylamine (ß-PEA)1 as well as methamphetamine2, an abused substance that has posed a severe threat to human health and society3. Given its unique physiological role in the brain, TAAR1 is also an emerging target for a range of neurological disorders including schizophrenia, depression and drug addiction2,4,5. Here we report structures of human TAAR1-G-protein complexes bound to methamphetamine and ß-PEA as well as complexes bound to RO5256390, a TAAR1-selective agonist, and SEP-363856, a clinical-stage dual agonist for TAAR1 and serotonin receptor 5-HT1AR (refs. 6,7). Together with systematic mutagenesis and functional studies, the structures reveal the molecular basis of methamphetamine recognition and underlying mechanisms of ligand selectivity and polypharmacology between TAAR1 and other monoamine receptors. We identify a lid-like extracellular loop 2 helix/loop structure and a hydrogen-bonding network in the ligand-binding pockets, which may contribute to the ligand recognition in TAAR1. These findings shed light on the ligand recognition mode and activation mechanism for TAAR1 and should guide the development of next-generation therapeutics for drug addiction and various neurological disorders.

Oligosaccharides increased both leaf biomass and steviol glycosides content of Stevia rebaudiana.

Steviol glycosides (SGs) are a variety of important natural sweeteners. They are 200-350 times sweeter than sucrose without calories. Currently, their production is still mainly dependent on extraction from Stevia rebaudiana Bertoni (stevia). Oligosaccharides are environmentally friendly elicitors that promote plant growth and accumulation of secondary metabolites. In the present study, different concentrations of chitosan oligosaccharides (COS) and alginate oligosaccharides (AOS) were applied to stevia to explore their effect on growth and SGs biosynthesis. It was found that both COS and AOS promoted biomass production by increasing the leaf number and photosynthetic efficiency, which may be related to the decreased content of abscisic acid. The content of SGs was significantly increased after 50 mg/L AOS treatment, which not only increased the contents of stevioside (STV) and rebaudioside A (Reb A) significantly, but some important minority glucosides, like Reb E, Reb D, and Reb M. The increased SGs contents were the combined effect of the higher expression of SGs biosynthesis related genes, including KAH, UGT74G1, UGT85C2, and UGT91D2. The geometry changes of stem induced by COS and AOS may help to increase the lodging resistance of stevia. Thus, COS and AOS can be used in the field planting of stevia to increase the yield of SGs for industrial purposes.

Ligand recognition and G protein coupling of the human itch receptor MRGPRX1.

MRGPRX1, a Mas-related GPCR (MRGPR), is a key receptor for itch perception and targeting MRGPRX1 may have potential to treat both chronic itch and pain. Here we report cryo-EM structures of the MRGPRX1-Gi1 and MRGPRX1-Gq trimers in complex with two peptide ligands, BAM8-22 and CNF-Tx2. These structures reveal a shallow orthosteric pocket and its conformational plasticity for sensing multiple different peptidic itch allergens. Distinct from MRGPRX2, MRGPRX1 contains a unique pocket feature at the extracellular ends of TM3 and TM4 to accommodate the peptide C-terminal "RF/RY" motif, which could serve as key mechanisms for peptidic allergen recognition. Below the ligand binding pocket, the G6.48XP6.50F6.51G6.52X(2)F/W6.55 motif is essential for the inward tilting of the upper end of TM6 to induce receptor activation. Moreover, structural features inside the ligand pocket and on the cytoplasmic side of MRGPRX1 are identified as key elements for both Gi and Gq signaling. Collectively, our studies provide structural insights into understanding itch sensation, MRGPRX1 activation, and downstream G protein signaling.

Fanzor is a eukaryotic programmable RNA-guided endonuclease.

RNA-guided systems, which use complementarity between a guide RNA and target nucleic acid sequences for recognition of genetic elements, have a central role in biological processes in both prokaryotes and eukaryotes. For example, the prokaryotic CRISPR-Cas systems provide adaptive immunity for bacteria and archaea against foreign genetic elements. Cas effectors such as Cas9 and Cas12 perform guide-RNA-dependent DNA cleavage1. Although a few eukaryotic RNA-guided systems have been studied, including RNA interference2 and ribosomal RNA modification3, it remains unclear whether eukaryotes have RNA-guided endonucleases. Recently, a new class of prokaryotic RNA-guided systems (termed OMEGA) was reported4,5. The OMEGA effector TnpB is the putative ancestor of Cas12 and has RNA-guided endonuclease activity4,6. TnpB may also be the ancestor of the eukaryotic transposon-encoded Fanzor (Fz) proteins4,7, raising the possibility that eukaryotes are also equipped with CRISPR-Cas or OMEGA-like programmable RNA-guided endonucleases. Here we report the biochemical characterization of Fz, showing that it is an RNA-guided DNA endonuclease. We also show that Fz can be reprogrammed for human genome engineering applications. Finally, we resolve the structure of Spizellomyces punctatus Fz at 2.7 Å using cryogenic electron microscopy, showing the conservation of core regions among Fz, TnpB and Cas12, despite diverse cognate RNA structures. Our results show that Fz is a eukaryotic OMEGA system, demonstrating that RNA-guided endonucleases are present in all three domains of life.

Benzene metabolite hydroquinone enhances self-renewal and proliferation of preleukemic cells through the Ppar-γ pathway.

Benzene is a known hematotoxic and leukemogenic chemical. Exposure to benzene cause inhibition of hematopoietic cells. However, the mechanism of how the hematopoietic cells inhibited by benzene undergo malignant proliferation is unknown. The cells carrying leukemia-associated fusion genes are present in healthy individuals and predispose the carriers to the development of leukemia. To identify the effects of benzene on hematopoietic cells, preleukemic bone marrow (PBM) cells derived from transgenic mice carrying the Mll-Af9 fusion gene were treated with benzene metabolite hydroquinone in serial replating of colony-forming unit (CFU) assay. RNA sequencing was further employed to identify the potential key genes that contributed to benzene-initiated self-renewal and proliferation. We found that hydroquinone induced a significant increase in colony formation in PBM cells. Peroxisome proliferator-activated receptor gamma (Ppar-γ) pathway, which plays a critical role in carcinogenesis in multiple tumors, was significantly activated after hydroquinone treatment. Notably, the increased numbers of the CFUs and total PBM cells induced by hydroquinone were significantly reduced by a specific Ppar-γ inhibitor (GW9662). These findings indicated that hydroquinone can enhance self-renewal and proliferation of preleukemic cells by activating the Ppar-γ pathway. Our results provide insight into the missing link between premalignant status and development of benzene-induced leukemia, which can be intervened and prevented.

Structural genomics of the human dopamine receptor system.

The dopaminergic system, including five dopamine receptors (D1R to D5R), plays essential roles in the central nervous system (CNS); and ligands that activate dopamine receptors have been used to treat many neuropsychiatric disorders, including Parkinson's Disease (PD) and schizophrenia. Here, we report cryo-EM structures of all five subtypes of human dopamine receptors in complex with G protein and bound to the pan-agonist, rotigotine, which is used to treat PD and restless legs syndrome. The structures reveal the basis of rotigotine recognition in different dopamine receptors. Structural analysis together with functional assays illuminate determinants of ligand polypharmacology and selectivity. The structures also uncover the mechanisms of dopamine receptor activation, unique structural features among the five receptor subtypes, and the basis of G protein coupling specificity. Our work provides a comprehensive set of structural templates for the rational design of specific ligands to treat CNS diseases targeting the dopaminergic system.

Structural basis for motilin and erythromycin recognition by motilin receptor.

Motilin is an endogenous peptide hormone almost exclusively expressed in the human gastrointestinal (GI) tract. It activates the motilin receptor (MTLR), a class A G protein-coupled receptor (GPCR), and stimulates GI motility. To our knowledge, MTLR is the first GPCR reported to be activated by macrolide antibiotics, such as erythromycin. It has attracted extensive attention as a potential drug target for GI disorders. We report two structures of Gq-coupled human MTLR bound to motilin and erythromycin. Our structures reveal the recognition mechanism of both ligands and explain the specificity of motilin and ghrelin, a related gut peptide hormone, for their respective receptors. These structures also provide the basis for understanding the different recognition modes of erythromycin by MTLR and ribosome. These findings provide a framework for understanding the physiological regulation of MTLR and guiding drug design targeting MTLR for the treatment of GI motility disorders.

Mechanism of hormone and allosteric agonist mediated activation of follicle stimulating hormone receptor.

Follicle stimulating hormone (FSH) is an essential glycoprotein hormone for human reproduction, which functions are mediated by a G protein-coupled receptor, FSHR. Aberrant FSH-FSHR signaling causes infertility and ovarian hyperstimulation syndrome. Here we report cryo-EM structures of FSHR in both inactive and active states, with the active structure bound to FSH and an allosteric agonist compound 21 f. The structures of FSHR are similar to other glycoprotein hormone receptors, highlighting a conserved activation mechanism of hormone-induced receptor activation. Compound 21 f formed extensive interactions with the TMD to directly activate FSHR. Importantly, the unique residue H6157.42 in FSHR plays an essential role in determining FSHR selectivity for various allosteric agonists. Together, our structures provide a molecular basis of FSH and small allosteric agonist-mediated FSHR activation, which could inspire the design of FSHR-targeted drugs for the treatment of infertility and controlled ovarian stimulation for in vitro fertilization.

Hormone- and antibody-mediated activation of the thyrotropin receptor.

Thyroid-stimulating hormone (TSH), through activation of its G-protein-coupled thyrotropin receptor (TSHR), controls the synthesis of thyroid hormone-an essential metabolic hormone1-3. Aberrant signalling of TSHR by autoantibodies causes Graves' disease (hyperthyroidism) and hypothyroidism, both of which affect millions of patients worldwide4. Here we report the active structures of TSHR with TSH and the activating autoantibody M225, both bound to the allosteric agonist ML-1096, as well as an inactivated TSHR structure with the inhibitory antibody K1-707. Both TSH and M22 push the extracellular domain (ECD) of TSHR into an upright active conformation. By contrast, K1-70 blocks TSH binding and cannot push the ECD into the upright conformation. Comparisons of the active and inactivated structures of TSHR with those of the luteinizing hormone/choriogonadotropin receptor (LHCGR) reveal a universal activation mechanism of glycoprotein hormone receptors, in which a conserved ten-residue fragment (P10) from the hinge C-terminal loop mediates ECD interactions with the TSHR transmembrane domain8. One notable feature is that there are more than 15 cholesterols surrounding TSHR, supporting its preferential location in lipid rafts9. These structures also highlight a similar ECD-push mechanism for TSH and autoantibody M22 to activate TSHR, therefore providing the molecular basis for Graves' disease.

Structural identification of lysophosphatidylcholines as activating ligands for orphan receptor GPR119.

Lysophosphatidylcholine (LPC) is an essential mediator in human lipid metabolism and is associated with a variety of diseases, but the exact identity of LPC receptors remains controversial. Through extensive biochemical and structural analyses, we have identified the orphan receptor GPR119 as the receptor for LPC. The structure of the GPR119-G-protein complex without any added ligands reveals a density map that fits well with LPC, which is further confirmed by mass spectrometry and functional studies. As LPCs are abundant on the cell membrane, their preoccupancy in the receptor may lead to 'constitutive activity' of GPR119. The structure of GPR119 bound to APD668, a clinical drug candidate for type 2 diabetes, reveals an exceedingly similar binding mode to LPC. Together, these data highlight structural evidence for LPC function in regulating glucose-dependent insulin secretion through direct binding and activation of GPR119, and provide structural templates for drug design targeting GPR119.

GPCRs steer Gi and Gs selectivity via TM5-TM6 switches as revealed by structures of serotonin receptors.

Serotonin (or 5-hydroxytryptamine, 5-HT) is an important neurotransmitter that activates 12 different G protein-coupled receptors (GPCRs) through selective coupling of Gs, Gi, or Gq proteins. The structural basis for G protein subtype selectivity by these GPCRs remains elusive. Here, we report the structures of the serotonin receptors 5-HT4, 5-HT6, and 5-HT7 with Gs, and 5-HT4 with Gi1. The structures reveal that transmembrane helices TM5 and TM6 alternate lengths as a macro-switch to determine receptor's selectivity for Gs and Gi, respectively. We find that the macro-switch by the TM5-TM6 length is shared by class A GPCR-G protein structures. Furthermore, we discover specific residues within TM5 and TM6 that function as micro-switches to form specific interactions with Gs or Gi. Together, these results present a common mechanism of Gs versus Gi protein coupling selectivity or promiscuity by class A GPCRs and extend the basis of ligand recognition at serotonin receptors.

Industry Distribution Characteristics of Benzene-Induced Leukemia - 7 PLADs, China, 2005-2019.

What is already known about this topic?: In the 1980s. benzene-induced leukemia (BIL) mainly occurred in shoemaking and painting industries. Now the industry distribution of benzene-induced leukemia may have changed over time. What is added by this report?: BlL cases mainly occurred in the manufacturing industry from 2005-2019, especially in private enterprises and small/medium-sized enterprises. The industry with the largest number of new cases of BIL was the general and special equipment manufacturing. The number of leukemia cases in emerging industries such as computer/electronic product manufacturing was found to be increasing. What are the implications for public health practice?: Strengthening supervision and regulation of manufacturing, especially of small/medium-sized enterprises and emerging manufacturing industry, may be effective in reducing BIL.

Research on the Error of Global Positioning System Based on Time Series Analysis.

Due to the poor dynamic positioning precision of the Global Positioning System (GPS), Time Series Analysis (TSA) and Kalman filter technology are used to construct the positioning error of GPS. According to the statistical characteristics of the autocorrelation function and partial autocorrelation function of sample data, the Autoregressive (AR) model which is based on a Kalman filter is determined, and the error model of GPS is combined with a Kalman filter to eliminate the random error in GPS dynamic positioning data. The least square method is used for model parameter estimation and adaptability tests, and the experimental results show that the absolute value of the maximum error of longitude and latitude, the mean square error of longitude and latitude and average absolute error of longitude and latitude are all reduced, and the dynamic positioning precision after correction has been significantly improved.

Structural insights into the ligand binding and Gi coupling of serotonin receptor 5-HT5A.

5-hydroxytryptamine receptor 5A (5-HT5A) belongs to the 5-HT receptor family and signals through the Gi/o protein. It is involved in nervous system regulation and an attractive target for the treatment of psychosis, depression, schizophrenia, and neuropathic pain. 5-HT5A is the only Gi/o-coupled 5-HT receptor subtype lacking a high-resolution structure, which hampers the mechanistic understanding of ligand binding and Gi/o coupling for 5-HT5A. Here we report a cryo-electron microscopy structure of the 5-HT5A-Gi complex bound to 5-Carboxamidotryptamine (5-CT). Combined with functional analysis, this structure reveals the 5-CT recognition mechanism and identifies the receptor residue at 6.55 as a determinant of the 5-CT selectivity for Gi/o-coupled 5-HT receptors. In addition, 5-HT5A shows an overall conserved Gi protein coupling mode compared with other Gi/o-coupled 5-HT receptors. These findings provide comprehensive insights into the ligand binding and G protein coupling of Gi/o-coupled 5-HT receptors and offer a template for the design of 5-HT5A-selective drugs.

Molecular insights into ligand recognition and activation of chemokine receptors CCR2 and CCR3.

Chemokine receptors are a family of G-protein-coupled receptors with key roles in leukocyte migration and inflammatory responses. Here, we present cryo-electron microscopy structures of two human CC chemokine receptor-G-protein complexes: CCR2 bound to its endogenous ligand CCL2, and CCR3 in the apo state. The structure of the CCL2-CCR2-G-protein complex reveals that CCL2 inserts deeply into the extracellular half of the transmembrane domain, and forms substantial interactions with the receptor through the most N-terminal glutamine. Extensive hydrophobic and polar interactions are present between both two chemokine receptors and the Gα-protein, contributing to the constitutive activity of these receptors. Notably, complemented with functional experiments, the interactions around intracellular loop 2 of the receptors are found to be conserved and play a more critical role in G-protein activation than those around intracellular loop 3. Together, our findings provide structural insights into chemokine recognition and receptor activation, shedding lights on drug design targeting chemokine receptors.

Structural insights into the peptide selectivity and activation of human neuromedin U receptors.

Neuromedin U receptors (NMURs), including NMUR1 and NMUR2, are a group of Gq/11-coupled G protein-coupled receptors (GPCRs). NMUR1 and NMUR2 play distinct, pleiotropic physiological functions in peripheral tissues and in the central nervous system (CNS), respectively, according to their distinct tissue distributions. These receptors are stimulated by two endogenous neuropeptides, neuromedin U and S (NMU and NMS) with similar binding affinities. NMURs have gathered attention as potential drug targets for obesity and inflammatory disorders. Specifically, selective agonists for NMUR2 in peripheral tissue show promising long-term anti-obesity effects with fewer CNS-related side effects. However, the mechanisms of peptide binding specificity and receptor activation remain elusive. Here, we report four cryo-electron microscopy structures of Gq chimera-coupled NMUR1 and NMUR2 in complexes with NMU and NMS. These structures reveal the conserved overall peptide-binding mode and the mechanism of peptide selectivity for specific NMURs, as well as the common activation mechanism of the NMUR subfamily. Together, these findings provide insights into the molecular basis of the peptide recognition and offer an opportunity for the design of the selective drugs targeting NMURs.

Molecular basis for allosteric agonism and G protein subtype selectivity of galanin receptors.

Peptide hormones and neuropeptides are complex signaling molecules that predominately function through G protein-coupled receptors (GPCRs). Two unanswered questions remaining in the field of peptide-GPCR signaling systems pertain to the basis for the diverse binding modes of peptide ligands and the specificity of G protein coupling. Here, we report the structures of a neuropeptide, galanin, bound to its receptors, GAL1R and GAL2R, in complex with their primary G protein subtypes Gi and Gq, respectively. The structures reveal a unique binding pose of galanin, which almost 'lays flat' on the top of the receptor transmembrane domain pocket in an α-helical conformation, and acts as an 'allosteric-like' agonist via a distinct signal transduction cascade. The structures also uncover the important features of intracellular loop 2 (ICL2) that mediate specific interactions with Gq, thus determining the selective coupling of Gq to GAL2R. ICL2 replacement in Gi-coupled GAL1R, µOR, 5-HT1AR, and Gs-coupled ß2AR and D1R with that of GAL2R promotes Gq coupling of these receptors, highlighting the dominant roles of ICL2 in Gq selectivity. Together our results provide insights into peptide ligand recognition and allosteric activation of galanin receptors and uncover a general structural element for Gq coupling selectivity.