Biology subjects

Yu, W.

Publications and source records attributed to Yu, W..

At least 163 records · Page 9Linked to original sources

bioRxiv2020

Transcription factors Aryl hydrocarbon receptor and TGF-inducible early gene are involved in an axis modulating immune response in mosquitoes

Immune homeostasis ensures effective pathogen defense and avoids overactivity, which is achieved through an orchestrated transcriptional network. Here we demonstrate that mosquito AhR and TIEG mediate a transcriptional axis to modulate the immune response. The AhR agonist compromised the immunity with reduced survival upon the challenge with bacterium Serratia fonticola, while the AhR antagonists enhanced the immunity with increased survival. The phenotype of pharmacological immune enhancement was corroborated genetically by the AhR gene silencing. The transcriptome comparison following AhR manipulations highlighted a set of AhR regulated genes, from which transcription factor TIEG, the ortholog of Kruppel-like factor 10, was chosen for further study. TIEG was required for the AhR mediated immune modulation. Silencing TIEG increased survival and reversed the immune suppression mediated by agonist-activated AhR. Among the transcriptomes, there were genes sharing co-expression patterns in the cohorts with AhR manipulation pharmacologically or genetically. Moreover, the mosquitoes with silenced TIEG and AhR shared ~68% altered genes upon infection. Together, the data suggest TIEG is downstream of AhR, acting as a major transcription factor mediating the immune modulation. The TIEG targets include genes involved in sugar metabolism and circadian rhythms, both processes are critical for immune homeostasis. In the naive mosquitoes, the AhR-TIEG axis prevents the adverse effect of the overactivated IMD pathway created by silencing the inhibitor Caspar. In summary, AhR and TIEG constitute a transcriptional axis that mediates a gene network critical for maintaining immune homeostasis. SignificanceImmune homeostasis is sustained by various parameters involving different transcriptional regulatory networks. Such knowledge in mosquitoes remains scarce. Here, using AhR manipulation and transcriptome interrogation, we demonstrate that AhR and TIEG (a KLF10 ortholog) constitute a transcriptional axis to mediate immune modulation using an antibacterial immune model in the malaria vector Anopheles gambiae. AhR is a ligand-activated transcription factor that senses environmental signals and transcribes relevant genes to modulate immune responses. TIEG/KLF10, conserved from invertebrates to mammals, mediates various transcriptional networks. Our data show that the AhR-TIEG axis controls the genes involving in sugar sensing and circadian rhythms in the infection context. This finding warrants further study to elucidate the transcriptional control of metabolic and circadian behind immune homeostasis.

immunology↗

bioRxiv2020

A long-range chromatin interaction regulates SATB homeobox 1 gene expression in trophoblast stem cells

SATB homeobox proteins are important regulators of developmental gene expression. Among the stem cell lineages determined during early embryonic development, trophoblast stem (TS) cells exhibit robust SATB expression. Both SATB1 and SATB2 act to maintain trophoblast stem-state. However, the molecular mechanisms that regulate TS-specific Satb expression are not yet known. We identified Satb1 variant 2 as the predominant transcript in trophoblasts. Histone marks, and RNA polymerase II occupancy in TS cells indicated active state of the promoter. A novel cis-regulatory region with active histone marks was identified [~]21kbp upstream of variant 2 promoter. CRISPR/Cas9 mediated disruption of this sequence decreased Satb1 expression in TS cells and chromatin conformation capture confirmed looping of this regulatory region into the promoter. Scanning position weight matrices across the enhancer predicted two ELF5 binding sites in close vicinity of SATB1 sites, which were confirmed by chromatin immunoprecipitation. Knockdown of ELF5 downregulated Satb1 expression in TS cells and overexpression of ELF5 increased the enhancer-reporter activity. Interestingly, ELF5 interacts with SATB1 in TS cells, and the enhancer activity was upregulated following SATB overexpression. Our findings indicate that trophoblast-specific Satb1 expression is regulated by long-range chromatin looping of an enhancer that interacts with ELF5 and SATB proteins.

developmental biology↗

bioRxiv2020

Bone marrow adipogenic lineage precursors (MALPs) promote osteoclastogenesis in bone remodeling and pathologic bone loss

Bone is maintained by coupled activities of bone-forming osteoblasts/osteocytes and bone-resorbing osteoclasts and an alternation of this relationship can lead to pathologic bone loss such as in osteoporosis. It is well known that osteogenic cells support osteoclastogenesis via synthesizing RANKL. Interestingly, our recently identified bone marrow mesenchymal cell population--marrow adipogenic lineage precursors (MALPs) that form a multi-dimensional cell network in bone--was computationally demonstrated to be the most interactive with monocyte-macrophage lineage cells through highly and specifically expressing several osteoclast regulatory factors, including RANKL. Using an adipocyte-specific Adipoq-Cre to label MALPs, we demonstrated that mice with RANKL deficiency in MALPs have a drastic increase of trabecular bone mass in long bones and vertebrae starting from 1 month of age but that their cortical bone is normal. This phenotype was accompanied by diminished osteoclast number and attenuated bone formation at the trabecular bone surface. Reduced RANKL signaling in calvarial MALPs also abolished osteolytic lesions after lipopolysaccharide (LPS) injections. Furthermore, in ovariectomized mice, elevated bone resorption was partially attenuated by RANKL deficiency in MALPs. In summary, our studies identified MALPs as a critical player in controlling bone remodeling during normal bone metabolism and pathological bone loss in a RANKL-dependent fashion.

cell biology↗

bioRxiv2020

Genome-Wide Mapping of Cisplatin Damaged Gene Loci

Cisplatin is a DNA targeting anticancer drug, yet its damaged gene loci have remained unclear. In the present work, combining affinity isolation and high throughput sequencing, we genome-widely mapped 17729 gene loci containing platination lesions, which mainly function as enzymes, transcription regulators, transporters and kinases, and of which 445 genes account for 71% of potential gene targets for cancer therapy reported in the literature. The most related core signaling pathway, disease and tissue toxicity of 7578 genes with an enrichment fold (EFG) of >12, where EFG refers to the ratio of total read counts of a gene detected in cells with and without cisplatin treatment, are sperm motility, cancer and hepatotoxicity with association P values of < 1x10-22. Among 616 kinase genes damaged by cisplatin, 427 are protein kinases which account for 82% of putative protein kinases, suggesting that cisplatin may act as broad-spectrum protein kinase inhibitor. Western Blot assays verified that expression of 8 important protein kinase genes was significantly reduced due to cisplatin damage. SPAG9 is closely related to 147 of 361 cancer diseases which the cisplatin damaged genes are associated with and was severely damaged by cisplatin. Given SPAG9 abundantly expresses JIP-4, a upstream mediator of protein kinase signaling, in testis, it may be responsible for the high sensitivity of testicular cancer to cisplatin, thus being a potential therapeutic target for precise treatment of testicular cancer. These findings provide novel insights into better understanding in molecular mechanism of anticancer activity and toxicity of cisplatin, more importantly inspire further studies in prioritizing gene targets for precise treatment of cancers.

pharmacology and toxicology↗

bioRxiv2020

Corticotropin-Releasing Factor Neurons in the Bed Nucleus of the Stria Terminalis Differentially Influence Pain Processing and Modulation in Male and Female Mice

The bed nucleus of the stria terminalis (BNST) plays an emerging yet understudied role in pain. Corticotropin-releasing factor (CRF) is an important source of pain modulation in the BNST, with local pharmacological inhibition of CRF receptors conditionally impacting the sensory and affective-motivational components of pain. Knowledge on how pain dynamically engages CRF neurons in the BNST and is influenced by intra-BNST production of CRF, however, remains unknown. In the present study, we utilized in vivo calcium imaging to show robust and synchronized recruitment of BNSTCRF+ neurons during acute exposure to noxious heat. Distinct patterns of recruitment were observed by sex, as the magnitude and timing of heat responsive activity in BNSTCRF+ neurons differed for male and female mice. We then established the necessity of CRF for intact pain behaviors by genetically deleting Crf in the BNST, which reduced thermal and mechanical nociceptive sensitivity for both sexes, and increased paw attending in female mice, suggesting a divergent role for CRF with respect to active coping responses to pain. Together, these findings demonstrate that CRF in the BNST contributes to multiple facets of the pain experience and may play a key role in the sex-specific expression of pain-related behaviors.

neuroscience↗

bioRxiv2020

Structural basis of a public antibody response to SARS-CoV-2

Molecular-level understanding of human neutralizing antibody responses to SARS-CoV-2 could accelerate vaccine design and facilitate drug discovery. We analyzed 294 SARS-CoV-2 antibodies and found that IGHV3-53 is the most frequently used IGHV gene for targeting the receptor binding domain (RBD) of the spike (S) protein. We determined crystal structures of two IGHV3-53 neutralizing antibodies +/- Fab CR3022 ranging from 2.33 to 3.11 [A] resolution. The germline-encoded residues of IGHV3-53 dominate binding to the ACE2 binding site epitope with no overlap with the CR3022 epitope. Moreover, IGHV3-53 is used in combination with a very short CDR H3 and different light chains. Overall, IGHV3-53 represents a versatile public VH in neutralizing SARS-CoV-2 antibodies, where their specific germline features and minimal affinity maturation provide important insights for vaccine design and assessing outcomes.

microbiology↗

bioRxiv2020

A putative long noncoding RNA-encoded micropeptide maintains cellular homeostasis in pancreatic β-cells

Micropeptides (microproteins) encoded by transcripts previously annotated as long noncoding RNA (IncRNAs) are emerging as important mediators of fundamental biological processes in health and disease. Here we applied two computational tools to identify putative micropeptides encoded by lncRNAs that are expressed in the human pancreas. We experimentally verified one such micropeptide encoded by a {beta}-cell- and neural cell-enriched lncRNA TUNAR (also known as TUNA, HI-LNC78 or LINC00617). We named this highly conserved 48-amino-acid micropeptide Beta cell- and Neural cell-regulin (BNLN). BNLN contains a single-pass transmembrane domain and localized at the endoplasmic reticulum in pancreatic {beta}-cells. Overexpression of BNLN lowered ER calcium levels, increased cytosolic calcium levels, and maintained ER homeostasis in response to high glucose challenge. To determine the physiological and pathological roles of BNLN, we assessed the BNLN expression in islets from mice fed with a high-fat diet and a regular diet, and found that BNLN is suppressed by diet-induced obesity (DIO). Conversely, overexpression of BNLN elevated glucose-stimulated insulin secretion in INS-1 cells. Lastly, BNLN overexpression enhanced insulin secretion in islets from lean and obese mice as well as from humans. Taken together, our study provides the first evidence that lncRNA-encoded micropeptides play a critical role in pancreatic {beta}-cell function and provides a foundation for future comprehensive analyses of micropeptide function and pathophysiological impact on diabetes.

molecular biology↗

bioRxiv2020

Fusarium verticillioides peroxins associated with peroxisomal docking/translocation module serve important roles in fumonisin biosynthesis and virulence

Peroxisomes are ubiquitous organelles in eukaryotic cells that fulfill various important metabolic functions. In this study, we investigated the role of Docking/Translocation Module (DTM) peroxins, mainly FvPex8, FvPex13, FvPex14, and FvPex33, in Fusarium verticillioides virulence and fumonisin B1 (FB1) biosynthesis. Protein interaction experiments suggested that FvPex13 serves as the core subunit of F. verticillioides DTM. When we generated gene deletion mutants ({Delta}Fvpex8, {Delta}Fvpex13, {Delta}Fvpex14, {Delta}Fvpex33, {Delta}Fvpex33/14) and examined whether the expression of other peroxin genes were affected in the DTM mutants, {Delta}Fvpex8 strain showed most drastic changes to PEX gene expression profiles. Deletion mutants exhibited disparity in carbon source utilization and defect in cell wall integrity when stress agents were applied. Under nutrient starvation, mutants also showed higher levels of lipid droplet accumulation. Notably, {Delta}Fvpex8 mutant showed significant FB1 reduction and altered expression of FUM1 and FUM19 genes. However, FvPex13 was primarily responsible for virulence, while {Delta}Fvpex33/14 double mutant also showed virulence defect. In summary, our study suggests that FvPex13 is the core component of DTM, regulating peroxisome membrane biogenesis as well as PTS1- and PTS2-mediated transmembrane cargo transportation. Importantly, we predict FvPex8 as a key component in DTM that affects peroxisome function in FB1 biosynthesis in F. verticillioides.

microbiology↗

bioRxiv2020

Susceptibility of tree shrew to SARS-CoV-2 infection

Since SARS-CoV-2 became a pandemic event in the world, it has not only caused huge economic losses, but also a serious threat to global public health. Many scientific questions about SARS-CoV-2 and COVID-19 were raised and urgently need to be answered, including the susceptibility of animals to SARS-CoV-2 infection. Here we tested whether tree shrew, an emerging experimental animal domesticated from wild animal, is susceptible to SARS-CoV-2 infection. No clinical signs were observed in SARS-CoV-2 inoculated tree shrews during this experiment except the increasing body temperature (above 39{degrees} C) particular in female animals during infection. Low levels of virus shedding and replication in tissues occurred in all three age groups, each of which showed his own characteristics. Histopathological examine revealed that pulmonary abnormalities were mild but the main changes although slight lesions were also observed in other tissues. In summary, tree shrew is not susceptible to SARS-CoV-2 infection and may not be a suitable animal for COVID-19 related researches.

microbiology↗

bioRxiv2020

Mico-Community associated with ectomycorrhizal Russula symbiosis and sporocarp-producing Russula in Fagaceae dominant nature areas in southern China

Russula griseocarnosa, an ectomycorrhizal (ECM) fungus, is a species of precious wild edible mushrooms with very high market value in southern China. Its yield is affected by many factors including the tree species and environmental conditions such as soil microbiome, humidity. How the microbiome promotes the ECM fungus symbiosis with Fagaceae plants and sporocarp-producing has never been studied. In this study, we collected rhizosphere samples from Fujian province, the microbiota in the root and mycorrhizal rhizosphere were identified by Illumina MiSeq high-throughput sequencing. First, we compared three types of fungal communities: root tips infected with ECM Russula (type 1), tips with Russula sporocarp (type 2) and tips without ECM (type 3). Our results showed that the fungal richness was negatively correlated with Russula. Russula, Tomentella and Lactarius were common in Fagaceae ECM roots. As to the mycorrhizal interactions, Boletus may be considered as an indicator species for sporocarp-producing Russula, and Acremonium, Cladophialophora were associated with Russula symbiosis. Second, we analyzed the fungal and bacterial communities in rhizosphere soils from the corresponding to previously three types (type 1, 2, 3). Dacryobolus and Acidocella may be considered as an indicator species for sporocarp-producing Russula. Fungi Tomentella, Saitozyma, Elaphomyces and bacteria Acidicaldus, Bryobacter, Sorangium and Acidobacterium occurred more frequently in the ECM Russula rhizosphere. Furthermore, the indicators Elaphomyces, Tomentella, Sorangium had a positive correlation with Russula symbiosis by network analyses. Overall, our results suggest a relationship between micro-community and ECM Russula formation and Russula sporocarp, which may provide new strategies for improving Russula symbiosis rate and sporocarp production.

ecology↗

bioRxiv2020

A New Resource for Genomics and Precision Health Information and Publications on the Investigation and Control of COVID-19 and other Coronaviruses

SummaryWe developed a new online database that contains the most updated published scientific literature, online news and reports, CDC and National Institutes of Health (NIH) resources. The tool captures emerging discoveries and applications of genomics, molecular, and other precision medicine and precision public health tools in the investigation and control of coronavirus diseases, including COVID-19, MERS-CoV, and SARS. AvailabilityCoronavirus Disease Portal (CDP) can be freely accessed via https://phgkb.cdc.gov/PHGKB/coVInfoStartPage.action. Contactwyu@cdc.gov

bioinformatics↗

bioRxiv2020

Comparison of SARS-CoV-2 infections among 3 species of non-human primates

COVID-19, caused by SARS-CoV-2 infection, has recently been announced as a pandemic all over the world. Plenty of diagnostic, preventive and therapeutic knowledges have been enriched from clinical studies since December 2019. However, animal models, particularly non-human primate models, are urgently needed for critical questions that could not be answered in clinical patients, evaluations of anti-viral drugs and vaccines. In this study, two families of non-human primates, Old world monkeys (12 Macaca mulatta, 6 Macaca fascicularis) and New world monkeys (6 Callithrix jacchus), were experimentally inoculated with SARS-CoV-2. Clinical signs were recorded. Samples were collected for analysis of viral shedding, viremia and histopathological examination. Increased body temperature was observed in 100% (12/12) M. mulatta, 33.3% (2/6) M. fascicularis and none (0/6) of C. jacchus post inoculation of SARS-CoV-2. All of M. mulatta and M. fascicularis showed chest radiographic abnormality. Viral genomes were detected in nasal swabs, throat swabs, anal swabs and blood from all 3 species of monkeys. Viral shedding from upper respiratory samples reached the peak between day 6 and day 8 post inoculation. From necropsied M. mulatta and M. fascicularis, the tissues showing virus positive were mainly lung, weasand, bronchus and spleen. No viral genome was seen in any of tissues from 2 necropsied C. jacchus. Severe gross lesions and histopathological changes were observed in lung, heart and stomach of SARS-CoV-2 infected animals. In summary, we have established a NHP model for COVID-19, which could be used to evaluate drugs and vaccines, and investigate viral pathogenesis. M. mulatta is the most susceptible to SARS-CoV-2 infection, followed by M. fascicularis and C. jacchus. One Sentence SummaryM. mulatta is the most susceptible to SARS-CoV-2 infection as compared to M. fascicularis and C. jacchus.

microbiology↗

bioRxiv2020

Automated Edge-Aware Refinement of Anatomical Atlases in 3D and Its Application to the Developing Mouse Brain

3D imaging data necessitate 3D reference atlases for accurate quantitative interpretation. Existing computational methods to generate 3D atlases from 2D-derived atlases result in extensive artifacts, while manual curation approaches are labor-intensive. We present a computational approach for 3D atlas construction that substantially reduces artifacts by identifying anatomical boundaries in the underlying imaging data and using these to guide 3D transformation. Anatomical boundaries also allow extension of atlases to complete edge regions. Applying these methods to the eight developmental stages in the Allen Developing Mouse Brain Atlas (ADMBA) led to more comprehensive and accurate atlases. We generated imaging data from fifteen whole mouse brains to validate atlas performance and observed qualitative and quantitative improvement (37% greater alignment between atlas and anatomical boundaries). We provide the methods as the MagellanMapper software and the eight 3D reconstructed ADMBA atlases. These resources facilitate whole-organ quantitative analysis between samples and across development.

bioinformatics↗

bioRxiv2020

Response of Asplenium nidus to Drought Stress and Identification of Drought Tolerance Genes

To explore how Asplenium nidus responds to drought stress, and to mine drought-responsive genes for Asplenium nidus, we conducted a pot experiment in the IOT smart greenhouse. We measured a series of physiological and biochemical indexes for drought-treated plants, and analyzed the expression of drought-responsive genes in Asplenium nidus by RT-qPCR. The results show that the Asplenium nidus is a species with drought tolerance. Asplenium nidus inhibits plant photosynthesis and reduces life activities by limiting stomatal opening to adapt to drought. To resist drought stress, the Asplenium nidus changes the osmotic potential by increasing the proline content to maintain normal metabolic activities and prevents the damage of active oxygen by increasing the enzyme activities of SOD and POD. Based on the analysis of the relative expression levels of genes, AVP1-2 and AVP1-4 may be drought-resistant genes in Asplenium nidus. This study lays the foundation for in-depth research on drought tolerance mechanisms and drought-resistant gene mining of Asplenium nidus.

genetics↗

bioRxiv2020

Neutralizing PD-L1 and PD-L2 Enhances the Efficacy of Immune Checkpoint Inhibitors in Ovarian Cancer.

Immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have improved for a number of solid tumors. Unfortunately, ovarian cancer represents a major clinical hurdle for immune checkpoint blockade (ICB) with reported low patient response rates. Using IHC staining, we find that PD-L2 is highly expressed in ovarian cancers and other malignancies with sub-optimal response to ICB, and is expressed at low levels in cancers responsive to ICB. Based on this observation, we hypothesized that the elevated expression of PD-L2 produced by both tumor and surrounding stromal cells contributes to immune-suppression. Since PD-L2 has been reported to have a 6- to10-fold higher native binding affinity to PD-1 compared with PD-L1, we hypothesized that high levels of PD-L2 can lead to insufficient blockade of the PD-1 signaling pathway. To overcome the immune repressive activity of PD-L2, we engineered a soluble PD-1 decoy molecule (sPD-1 mutant) that binds and neutralizes both PD-L1 and PD-L2 with a 10,000- and 200- fold improvement in binding affinity, respectively, when compared to wild-type binding to these same molecules. Such enhancement in binding affinity is facilitated by amino acid mutations both within and outside of the binding interface. Furthermore, this high affinity sPD-1 mutant molecule demonstrates superior in vivo efficacy in multiple cancer models including ovarian cancer where PD-L2 is highly expressed on the cell surface. One Sentence SummaryDual Inhibition of PD-L1 and PD-L2 using an affinity enhanced sPD-1 decoy molecule delivers superior antitumor activity when compared with PD-1 and PD-L1 antibodies in ovarian cancer.

cancer biology↗

bioRxiv2019

Developmental trajectory of pre-hematopoietic stem cell formation fromendothelium

Hematopoietic stem and progenitor cells (HSPCs) differentiate from hemogenic endothelial (HE) cells through an endothelial to hematopoietic cell transition (EHT). Newly formed HSPCs accumulate in intra-arterial clusters (IACs) before colonizing the fetal liver. To examine the cell and molecular transitions during the EHT, and the heterogeneity of HSPCs within IACs, we profiled [~]37,000 cells from the caudal arteries of embryonic day 9.5 (E9.5) to E11.5 mouse embryos by single-cell transcriptome and chromatin accessibility sequencing. We identified an intermediate developmental stage prior to HE that we termed pre-HE, characterized by increased accessibility of chromatin enriched for SOX, FOX, GATA, and SMAD motifs. A developmental bottleneck separates pre-HE from HE, with RUNX1 dosage regulating the efficiency of the pre-HE to HE transition. Distinct developmental trajectories within IAC cells result in two populations of CD45+ HSPCs; an initial wave of lympho-myeloid-biased progenitors, followed by precursors of hematopoietic stem cells (pre-HSCs).

developmental biology↗

bioRxiv2019

Programmable CRISPR interference for gene silencing using Cas13a in mosquitoes

In the CRISPR-Cas systems, Cas13a is an RNA-guided RNA nuclease specifically targeting single strand RNA. We developed a Cas13a mediated CRISPR interference tool to target mRNA for gene silencing in mosquitoes. The machinery was tested in two mosquito species. A Cas13a expressing plasmid was delivered to mosquitoes by intrathoracic injection, and Cas13a transcripts were detectable at least10 days post-delivery. In Anopheles gambiae, vitellogenin gene was silenced by Vg-crRNA injection two hours post-blood meal, which was accompanied by a significant reduction in egg production. In Aedes aegypti, the - and {delta}-subunits of COPI genes were silenced by a post-blood meal crRNA injection, which resulted in mortality and fragile midguts, reproducing a phenotype reported previously. Co-silencing genes simultaneously is achievable when a cocktail of target crRNAs is given. No detectable collateral cleavages of non-target transcripts were observed in the study. This study adds a programmable CRISPR tool to manipulate RNA in mosquitoes.

molecular biology↗

bioRxiv2019

Structure of the cell-binding component of the Clostridium difficile binary toxin reveals a novel macromolecular assembly

Targeting Clostridium difficile infection (CDI) is challenging because treatment options are limited, and high recurrence rates are common. One reason for this is that hypervirulent CDI often has a binary toxin termed the C. difficile toxin (CDT), in addition to the enterotoxins TsdA and TsdB. CDT has an enzymatic component, termed CDTa, and a pore-forming or delivery subunit termed CDTb. CDTb was characterized here using a combination of single particle cryoEM, X-ray crystallography, NMR, and other biophysical methods. In the absence of CDTa, two novel di-heptamer structures for activated CDTb (aCDTb; 1.0 MDa) were solved at atomic resolution including a symmetric (SymCDTb; 3.14 [A]) and an asymmetric form (AsymCDTb; 2.84 [A]). Roles played by two receptor-binding domains of aCDTb were of particular interest since RBD1 lacks sequence homology to any other known toxin, and the RBD2 domain is completely absent in other well-studied heptameric toxins (i.e. anthrax). For AsymCDTb, a novel Ca2+ binding site was discovered in RBD1 that is important for its stability, and RBD2 was found to be critical for host cell toxicity and the novel di-heptamer fold for both forms of aCDTb. Together, these studies represent a starting point for structure-based drug-discovery strategies to targeting CDT in the most severe strains of CDI. SIGNIFICANCE STATEMENTThere is a high burden from C. difficile infection (CDI) throughout the world, and the Center for Disease Control (CDC) reports more than 500,000 cases annually in the United States, resulting in an estimated 15,000 deaths. In addition to the large clostridial toxins, TcdA/TcdB, a third C. difficile binary toxin (CDT) is associated with the most serious outbreaks of drug resistant CDI in the 21st century. Here, structural biology and biophysical approaches were used to characterize the cell binding component of CDT, termed CDTb, at atomic resolution. Surprisingly, two novel structures were solved from a single sample that help to explain the molecular underpinnings of C. difficile toxicity. These structures will also be important for targeting this human pathogen via structure-based therapeutic design methods.

biophysics↗