Biology subjects

Gao, B.

Publications and source records attributed to Gao, B..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

The long-chain fatty acid-CoA ligase FadD1 monitors Pseudomonas aeruginosa quorum sensing as a receptor of cis-2-decenoic acid

Diffusible signal factor (DSF)-family quorum sensing (QS) signals are widely utilized by many bacterial pathogens to modulate various biological functions and virulence. Previous studies showed that cis-2-decenoic acid (cis-DA) is involved in modulation of biofilm dispersion in Pseudomonas aeruginosa, but its signaling mechanism remains vague. Here, we report that cis-DA regulates the physiology and virulence of P. aeruginosa through the long-chain fatty acid-CoA ligase FadD1. Cis-DA specifically binds to FadD1 with high affinity and enhances the binding of FadD1 to the promoter DNA region of lasR. Further analysis showed that the FadD1 is a response regulator of cis-DA with a DNA-binding leucine zipper motif to control the transcription of various target genes. Moreover, FadD1 exhibited catalytic activity on cis-2-dodecenoic acid (BDSF) of Burkholderia cenocepacia and enhanced the competitiveness of P. aeruginosa. Together, our work presents a new DSF-type QS signaling system, which is highlighted by its receptor and response regulator evolved from a canonical enzyme of fatty acid metabolism. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/598097v2_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@66b8aaorg.highwire.dtl.DTLVardef@1e5b9b9org.highwire.dtl.DTLVardef@1043525org.highwire.dtl.DTLVardef@13d3ed1_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsThe long-chain fatty acid-CoA ligase FadD1 acts as a global transcriptional regulator in P. aeruginosa. FadD1 is a receptor of QS signal cis-DA and functions at the top of the QS hierarchy in P. aeruginosa. The homolog of FadD1 in P. fluorescens could bind to the target gene promoter by responding to cis-DA. In briefPseudomonas aeruginosa is a human pathogen with antibiotic resistance and a wide range of dynamic defenses makes it an extremely challenging organism to treat in modern-day medicine. It employs cis-2-decenoic acid (cis-DA) quorum sensing to regulate the physiology and pathogenesis. Song et al. demonstrate that the long-chain fatty acid-CoA ligase FadD1 controls the important biological functions and virulence in P. aeruginosa as a novel response regulator of cis-DA signal.

microbiology↗

bioRxiv2024

Parkinson's Disease-Linked Kir4.2 Mutation R28C Leads to Loss of Ion Channel Function

Parkinsons disease (PD) is a complex, progressive neurodegenerative disorder driven by multiple pathogenetic factors, including oxidative stress, mitochondria dysfunction, neuroinflammation, and ion imbalance. Recent evidence highlights the significant role of potassium channels in the pathophysiology of PD. We recently identified a PD-linked genetic mutation in the KCNJ15 gene (KCNJ15p.R28C), encoding the inwardly rectifying potassium channel Kir4.2, within a four-generation family with familial PD. However, the role of the Kir4.2 channel in neurodegenerative diseases remains largely unexplored. This study aimed to elucidate the impact of the KCNJ15p.R28C (Kir4.2R28C) mutation on the biophysical and biochemical properties of Kir4.2. Employing Kir4.2-overexpressing HEK293T cells as a model, we investigated how the mutation affects the channels functional properties, total protein expression, intracellular processing in the endoplasmic reticulum and lysosomes, and plasma membrane trafficking. Patch clamp studies revealed that the Kir4.2R28C mutation results in loss of channel function with significant dominant-negative effects. This dysfunction is partially attributed to the substantial reduction in overall mutant channel protein expression compared to the wild-type (Kir4.2WT). We observed that both Kir4.2WT and Kir4.2R28C proteins undergo glycosylation during the post-translational modification process, albeit with differing protein turnover efficiencies. Furthermore, the Kir4.2R28C mutant exhibits reduced stability and compromised plasma membrane trafficking capacity compared to Kir4.2WT. These findings suggest that the Kir4.2R28C mutant has unique biomolecular and biophysical characteristics distinct from the Kir4.2WT channel, which potentially elucidates its role in the pathogenesis of PD. Key Points[tpltrtarr] Inwardly rectifying potassium channels are increasingly recognized for their critical role in the complex pathogenesis of Parkinsons disease (PD) [tpltrtarr]We previously identified a genetic mutation, Kir4.2R28C, in the inwardly rectifying potassium channel Kir4.2, which strongly segregates with familial PD in a multi- generational pedigree. [tpltrtarr]This study confirms Kir4.2R28C as a loss-of-function mutation with significant dominant- negative effects, impairing channel activity even in heterozygous conditions. [tpltrtarr]The Kir4.2R28C mutation significantly reduces overall protein levels, impairs protein stability and disrupts plasma membrane trafficking in in vitro cell models.

cell biology↗

bioRxiv2024

Synthetic coevolution reveals adaptive mutational trajectories of neutralizing antibodies and SARS-CoV-2

The Covid-19 pandemic showcases a coevolutionary race between the human immune system and SARS-CoV-2, mirroring the Red Queen hypothesis of evolutionary biology. The immune system generates neutralizing antibodies targeting the SARS-CoV-2 spike proteins receptor binding domain (RBD), crucial for host cell invasion, while the virus evolves to evade antibody recognition. Here, we establish a synthetic coevolution system combining high-throughput screening of antibody and RBD variant libraries with protein mutagenesis, surface display, and deep sequencing. Additionally, we train a protein language machine learning model that predicts antibody escape to RBD variants. Synthetic coevolution reveals antagonistic and compensatory mutational trajectories of neutralizing antibodies and SARS-CoV-2 variants, enhancing the understanding of this evolutionary conflict.

synthetic biology↗

bioRxiv2023

Bacterial vitamin B6 required for post-embryonic development in C. elegans

Nutritional intake influences animal growth, reproductive capacity, and survival of animals. Under nutrition deficiency, animal developmental arrest occurs as an adaptive strategy to survive. However, the nutritional basis and the underlying nutrient sensing mechanism essential for initiating animal regrowth after developmental arrest remain to be explored. In Caenorhabditis elegans, larvae undergo early developmental arrest are stress resistant, and they require certain nutrients to initiate postembryonic development. Here, we investigated the developmental arrest in C. elegans feeding on Lactobacillus plantarum, and the rescue of the diapause state with trace supplementation of Escherichia coli. We performed a genome-wide screen using 3983 individual gene deletion E. coli mutants and identified E. coli genes that are indispensable for C. elegans larval growth on original not nutritionally sufficient bacteria L. plantarum. Among these crucial genes, we confirmed E. coli pdxH, and the downstream metabolite pyridoxal 5-P (PLP, Vitamin B6) as essential nutritional factors initiating C. elegans postembryonic development. Transcriptome results suggest that bacterial pdxH affects host development by coordinating host metabolic processes and PLP binding. Additionally, bacterial PLP may act as a cofactor for host tyrosine aminotransferase, thereby promoting the translocation of daf-16 to nucleus. Altogether, these results highlight the role of microbial metabolite PLP as a crucial micronutrient to recover postembryonic development in C. elegans.

developmental biology↗

bioRxiv2023

Deep learning-guided selection of antibody therapies with enhanced resistance to current and prospective SARS-CoV-2 Omicron variants

Most COVID-19 antibody therapies rely on binding the SARS-CoV-2 receptor binding domain (RBD). However, heavily mutated variants such as Omicron and its sublineages, which are characterized by an ever increasing number of mutations in the RBD, have rendered prior antibody therapies ineffective, leaving no clinically approved antibody treatments for SARS-CoV-2. Therefore, the capacity of therapeutic antibody candidates to bind and neutralize current and prospective SARS-CoV-2 variants is a critical factor for drug development. Here, we present a deep learning-guided approach to identify antibodies with enhanced resistance to SARS-CoV-2 evolution. We apply deep mutational learning (DML), a machine learning-guided protein engineering method to interrogate a massive sequence space of combinatorial RBD mutations and predict their impact on angiotensin-converting enzyme 2 (ACE2) binding and antibody escape. A high mutational distance library was constructed based on the full-length RBD of Omicron BA.1, which was experimentally screened for binding to the ACE2 receptor or neutralizing antibodies, followed by deep sequencing. The resulting data was used to train ensemble deep learning models that could accurately predict binding or escape for a panel of therapeutic antibody candidates targeting diverse RBD epitopes. Furthermore, antibody breadth was assessed by predicting binding or escape to synthetic lineages that represent millions of sequences generated using in silico evolution, revealing combinations with complementary and enhanced resistance to viral evolution. This deep learning approach may enable the design of next-generation antibody therapies that remain effective against future SARS-CoV-2 variants.

immunology↗

bioRxiv2023

Bacterial purine metabolism modulates C. elegans development and stress tolerance via DAF-16 translocation

Purine homeostasis is crucial for cellular function and is a conserved metabolic network from prokaryotes to humans. While extensively studied in microorganisms like yeast and bacteria, the impact of perturbed dietary purine levels on animal development and balanced growth remains poorly understood. To investigate the mechanisms underlying this deficiency, we utilized Caenorhabditis elegans as the metazoan model. Through a high-throughput screening of an E. coli mutant library Keio collection, we identified 34 E. coli mutants that delay C. elegans development. Among these mutants, we found that E. coli purE gene is an essential genetic component that promotes host development in a dose-dependent manner. Additionally, we observed increased nuclear accumulation of the FoxO transcription factor DAF-16 when fed E. coli purE- mutants, suggesting the role of DAF-16 in response to nutrient, especially purine deficiency. RNA-seq analysis and phenotype assays revealed that worms fed the E. coli purE mutant exhibited elevated lifespan, thermotolerance, and pathogen resistance. These findings collectively suggest that perturbations in bacterial purine metabolism likely serve as a cue to promote development and activate the defense response in the nematode C. elegans through DAF-16 nuclear translocation.

developmental biology↗

bioRxiv2023

Proteome-Wide Association Studies for Blood Lipids and Comparison with Transcriptome-Wide Association Studies

Blood lipid traits are treatable and heritable risk factors for heart disease, a leading cause of mortality worldwide. Although genome-wide association studies (GWAS) have discovered hundreds of variants associated with lipids in humans, most of the causal mechanisms of lipids remain unknown. To better understand the biological processes underlying lipid metabolism, we investigated the associations of plasma protein levels with total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) in blood. We trained protein prediction models based on samples in the Multi-Ethnic Study of Atherosclerosis (MESA) and applied them to conduct proteome-wide association studies (PWAS) for lipids using the Global Lipids Genetics Consortium (GLGC) data. Of the 749 proteins tested, 42 were significantly associated with at least one lipid trait. Furthermore, we performed transcriptome-wide association studies (TWAS) for lipids using 9,714 gene expression prediction models trained on samples from peripheral blood mononuclear cells (PBMCs) in MESA and 49 tissues in the Genotype-Tissue Expression (GTEx) project. We found that although PWAS and TWAS can show different directions of associations in an individual gene, 40 out of 49 tissues showed a positive correlation between PWAS and TWAS signed p-values across all the genes, which suggests a high-level consistency between proteome-lipid associations and transcriptome-lipid associations.

genomics↗

bioRxiv2023

Enzyme-mediated alkynylation enables transcriptome-wide identification of pseudouridine modifications

Pseudouridine ({Psi}) is one of the most abundant chemical modifications that exists in various types of RNA species and is known to play important roles in RNA function. The advances in studies of {Psi} in less abundant messenger RNA species have been hindered by a lack of suitable methods to precisely and sensitively map their distributions. Here we show that a methyltransferase from Methanocaldococcus jannaschii can label RNA {Psi} efficiently and specifically with various functional groups, both in isolated RNA and inside cells. We leveraged this enzymatic labeling strategy to develop ELAP-seq as a facile method to enrich {Psi}-modified transcripts for the detection of {Psi} modifications at single base resolution with high sensitivity and low background. Using this method, we identified over 10, 000 candidate {Psi} sites from human transcripts, which provides new insights into {Psi} biosynthesis and function. Our study provides a chemical biology method that specifically labels {Psi} for its detection and functional alteration.

biochemistry↗

bioRxiv2023

Coronavirus endoribonuclease nsp15 induces host cellular protein synthesis shutoff

The endoribonuclease (EndoU) nsp15 of coronaviruses plays an important role in evasion of host innate immune responses by reducing the abundance of viral double-stranded RNA, whereas less is known about potential host cellular targets of nsp15. In this study, we show that cellular protein synthesis is inhibited upon over-expression of nsp15 from four genera of coronaviruses and this is accompanied by nuclear retention of the poly(A) binding protein cytoplasmic 1 (PABPC1). We also show that the EndoU activity of nsp15 is indispensable for both, inhibition of protein synthesis and PABPC1 nuclear relocation. FISH analysis using oligo-dT probes, revealed an overlap between the localization of cellular mRNA and that of overexpressed nsp15 in some cells, suggesting that, when expressed alone, nsp15 may target host mRNA. When investigating the association of nsp15 on protein shut off in the context of a viral infection, we observed that the{gamma} -coronavirus infectious bronchitis virus (IBV), induced host translation shutoff in an p-eIF2-independent manner and mainly retained PABPC1 in the cytoplasm, whereas the nsp15 EndoU-deficient IBV accumulated viral dsRNA and caused p-PKR-p-eIF2-dependent host protein translation shutoff, accompanied with PABPC1 nuclear relocation or stress granule (SG) localization. This phenomenon suggests that during infection with wild type IBV, although the cellular translation is inhibited, initiation of viral mRNA translation leads to PABPC1 binding to viral mRNA, thereby preventing its nuclear entry; during infection with nsp15 EndoU-deficient IBV however, the eIF2-dependent host protein translation shutoff prevents both host and viral mRNA translation initiation, releasing PABPC1 from binding to cytosolic and viral mRNA, thereby relocating it to the nucleus or to SG. Altogether, this study reveals unique yet conserved mechanisms of host protein shutoff that add to our understanding of how coronaviruses regulate host protein expression through a mechanism that involves catalytically active nsp15 EndoU, and describes how nsp15 may target both, viral and host mRNA. Author summaryIt has been reported that coronavirus infection suppresses host protein translation, - and {beta}- coronavirus nsp1 is responsible for inhibition of host gene expression. However, for{gamma} - and{delta} -coronavirus, there is no nsp1 and the underlying mechanisms by which virus regulates host translation are not well characterized. Here, we show that coronavirus endoribonuclease nsp15 is responsible for the inhibition of host translation by targeting to host factors, meanwhile it helps virus bypass the PKR-eIF2 mediated host translation shutoff, which is harmful for virus gene expression, by reducing the accumulation of viral dsRNA. This novel finding gives insight how does nsp15 targets to both host factors and viral RNA, to facilitate virus replication. Moreover, the novel function of nsp15 is found to be conserved among coronaviruses, revealing the essential role of this endoribonuclease in hijacking host translation machinery for virus replication.

microbiology↗

bioRxiv2023

Discovery and characterization of cross-reactive intrahepatic antibodies in severe alcoholic hepatitis

The pathogenesis of antibodies in severe alcoholic hepatitis (SAH) remains unknown. We sought to determine if there was antibody deposition in SAH livers and whether antibodies extracted from SAH livers were cross-reactive against both bacterial antigens and human proteins. We analyzed immunoglobulins (Ig) in explanted livers from SAH patients (n=45) undergoing liver transplantation and tissue from corresponding healthy donors (HD, n=10) and found massive deposition of IgG and IgA isotype antibodies associated with complement fragment C3d and C4d staining in ballooned hepatocytes in SAH livers. Ig extracted from SAH livers, but not patient serum exhibited hepatocyte killing efficacy in an antibody-dependent cell-mediated cytotoxicity (ADCC) assay. Employing human proteome arrays, we profiled the antibodies extracted from explanted SAH, alcoholic cirrhosis (AC), nonalcoholic steatohepatitis (NASH), primary biliary cholangitis (PBC), autoimmune hepatitis (AIH), hepatitis B virus (HBV), hepatitis C virus (HCV) and HD livers and found that antibodies of IgG and IgA isotypes were highly accumulated in SAH and recognized a unique set of human proteins as autoantigens. The use of an E. coli K12 proteome array revealed the presence of unique anti-E. coli antibodies in SAH, AC or PBC livers. Further, both Ig and E. coli captured Ig from SAH livers recognized common autoantigens enriched in several cellular components including cytosol and cytoplasm (IgG and IgA), nucleus, mitochondrion and focal adhesion (IgG). Except IgM from PBC livers, no common autoantigen was recognized by Ig and E. coli captured Ig from AC, HBV, HCV, NASH or AIH suggesting no cross-reacting anti-E. coli autoantibodies. The presence of cross-reacting anti-bacterial IgG and IgA autoantibodies in the liver may participate in the pathogenesis of SAH.

pathology↗

bioRxiv2023

Measuring chondrocyte viability of articular cartilage based on label-free two-photon microscopy and deep learning image analysis

ObjectiveChondrocyte viability (CV) is an important indicator of articular cartilage health. Two-photon excitation autofluorescence (TPAF) and second harmonic generation (SHG) microscopy provide a label-free method for imaging chondrocytes. In this study, we propose an automated assessment of CV using deep learning cell segmentation and counting based on acquired TPAF/SHG images. DesignLabel-free TPAF/SHG images of cartilage samples from rats and porcine were acquired using both commercial and home-built two-photon microscopes, respectively. TPAF/SHG images were merged to form RGB color images with red, green, and blue channels assigned to TPAF (two channels) and SHG signals, respectively. To make the training datasets for the deep learning networks, individual chondrocyte areas on the RGB color images were manually circled and live or dead chondrocytes were validated by using Calcein-AM and Ethidium homodimer-1 dye labeling. We first built a chondrocyte viability network (MCV-Net) using the Mask R-CNN architecture, which could provide individual segmented cellular areas with live or dead status. Wiener deconvolution preprocessing was added before the input of MCV-Net to improve the accuracy of the CV analysis, forming the Wiener deconvolution CV network (wMCV-Net). ResultsTraining (300 images) and test (120 images) datasets were built for rats and porcine cartilage respectively. Wiener deconvolution could improve the Peak Signal-to-Noise Ratio (PSNR) for 30-40%. We demonstrated that both MCV-Net and wMCV-Net significantly improved the accuracy of the CV measurement. ConclusionA custom desktop TPAF/SHG microscope was used in collaboration with deep learning algorithm wMCV-Net based label-free method to assess the CV and get 95% accuracy with both rats and porcine samples.

bioengineering↗

bioRxiv2022

Visualization of mitochondrial cristae and mtDNA evolvement and interactions with super-resolution microscopy

Mitochondrial cristae host the respiratory chain complexes composed of mitochondrial DNA (mtDNA)-encoded and nuclear-encoded proteins and are responsible for ATP production. Movement of mtDNA located in the matrix is limited due to blockade by the cristae; yet, the dynamic interaction between the inner membrane and mtDNA remains unknown due to the insufficient spatiotemporal resolution of conventional microscopy and the lack of appropriate in vivo probes targeted to the mitochondrial inner membrane. Here, we developed a novel fluorescence probe to visualize the inner membrane using low-power stimulated emission depletion (STED) microscopy. Dual-color imaging of the inner membrane and mtDNA demonstrated that mtDNA is more likely to spread at mitochondrial tips or branch points under an overall even distribution. Interestingly, exploration of forming this distribution propensity uncovered that the mitochondrial dynamics are closely related to the location of mtDNA, and further insight found that fusion always occurs near mtDNA in order to minimize the pressure for cristae remodeling. In healthy cells, mitochondrial dynamics based on cristae remodeling promotes the even distribution of mtDNA, on the contrary, when cristae structure fails in apoptosis and ferroptosis, leading to mtDNA distribution disorder. Observation of active changes during apoptosis further captured the dynamic process of inner membrane herniation and mtDNA leakage along with cristae remodeling. Under ferroptosis, the mitochondria shrank into ellipsoids and mtDNA converged at the center of mitochondria. The rich dynamics between the cristae and mtDNA, revealed at unprecedented spatiotemporal resolution, show the motive and outgrowth of mtDNA distribution.

biophysics↗

bioRxiv2022

Open-3DSIM: an Open-source three-dimensional structured illumination microscopy reconstruction platform

With optical section and defocus removal effect, three-dimensional structured illumination microscopy (3DSIM) can get a whole sight of intracellular organelle. Here, Open-3DSIM is reported as an open-source reconstruction platform with double improvement on lateral and axial resolution. MATLAB code, ImageJ version and Exe application are provided for biologists and engineers to maximize its user-friendliness and prompt its further development. Through adaptive parameter estimation and spectrum filter optimization, we demonstrate its superior performance of artifact suppression and defocus elimination over other algorithms on various specimens, under gradient signal-to-noise levels. Moreover, with the capacity to extract the dipole orientation, Open-3DSIM paves a new avenue for interpreting the subcellular structures in six dimensions (xyz{theta}{lambda}t).

bioengineering↗

bioRxiv2022

Arabidopsis AAR2, a conserved splicing factor in eukaryotes, acts in microRNA biogenesis

MicroRNAs (miRNAs) play an essential role in plant growth and development, and as such, their biogenesis is fine-tuned via regulation of the core microprocessor components. Here, we report that Arabidopsis AAR2, a homolog of a U5 snRNP assembly factor in yeast and humans, not only acts in splicing but also promotes miRNA biogenesis. AAR2 interacts with the microprocessor component HYPONASTIC LEAVES1 (HYL1) in the cytoplasm, nucleus and dicing bodies. In aar2 mutants, abundance of nonphosphorylated HYL1, the active form of HYL1, and the number of HYL1-labeled dicing bodies are reduced. Primary miRNA (pri-miRNA) accumulation is compromised despite normal promoter activities of MIR genes in aar2 mutants. RNA decay assays show that the aar2-1 mutation leads to faster degradation of pri-miRNAs in a HYL1-dependent manner, which reveals a previously unknown and negative role of HYL1 in miRNA biogenesis. Taken together, our findings reveal a dual role of AAR2 in miRNA biogenesis and pre-mRNA splicing. SignificanceIn yeast and humans, AAR2 is involved in pre-mRNA splicing through regulating U5 snRNP assembly. This study shows that Arabidopsis AAR2 promotes microRNA (miRNA) accumulation in addition to its conserved role in pre-mRNA splicing. AAR2 is associated with the microprocessor component HYL1 and promotes its dephosphorylation to produce the active form in miRNA biogenesis. The study also reveals a previously unknown role of HYL1 in causing the degradation of the primary precursors to miRNAs (pri-miRNAs) and a role of AAR2 in protecting pri-miRNAs from HYL1-depedent degradation. Taken together, our findings provide new insights into the role of a conserved splicing factor in miRNA biogenesis in plants.

plant biology↗

bioRxiv2022

Evolutionary Principles of Bacterial Signaling Capacity and Complexity

Microbes rely on signal transduction systems to sense and respond to environmental changes for survival and reproduction. It is generally known that niche adaptation plays an important role in shaping the signaling repertoire. However, the evolution of bacterial signaling capacity lacks systematic studies with a temporal direction. Particularly, it is unclear how complexity evolved from simplicity or vice versa for signaling networks. Here we examine the evolutionary processes of major signal transduction systems in Campylobacterota (formerly Epsilonproteobacteria), a phylum with sufficient evolutionary depth and ecological diversity. Evolution of signaling systems within Campylobacterota shows two opposite trends. During niche expansion, signaling complexity increases with gene expansions through horizontal gene transfer (HGT), gene duplication, fusion and fission, which create opportunities for genetic innovation and pathway integration. In contrast, as the lineages adapt to a specialized niche, complexity decreases with massive gene losses that lead to the decline or disappearance of pathways mediated by multiple transmitters. Overall, signaling capacity and complexity arise and drop together in Campylobacterota, determined by sensory demand, genetic resources and co-evolution within the genomic context. These findings reflects plausible evolutionary principles for other cellular networks and genome evolution of the Bacteria domain.

microbiology↗

bioRxiv2021

Predictive profiling of SARS-CoV-2 variants by deep mutational learning

The continual evolution of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the emergence of variants that show resistance to vaccines and neutralizing antibodies (1-4) threaten to prolong the coronavirus disease 2019 (COVID-19) pandemic (5). Selection and emergence of SARS-CoV-2 variants are driven in part by mutations within the viral spike protein and in particular the ACE2 receptor-binding domain (RBD), a primary target site for neutralizing antibodies. Here, we develop deep mutational learning (DML), a machine learning-guided protein engineering technology, which is used to interrogate a massive sequence space of combinatorial mutations, representing billions of RBD variants, by accurately predicting their impact on ACE2 binding and antibody escape. A highly diverse landscape of possible SARS-CoV-2 variants is identified that could emerge from a multitude of evolutionary trajectories. DML may be used for predictive profiling on current and prospective variants, including highly mutated variants such as omicron (B.1.1.529), thus supporting decision making for public heath as well as guiding the development of therapeutic antibody treatments and vaccines for COVID-19.

synthetic biology↗

bioRxiv2021

A CRISPR-Cas assisted shotgun mutagenesis method for evolutionary genome engineering

Genome mutagenesis drives the evolution of organisms. Here, we developed a CRISPR-Cas assisted random mutation (CARM) technology for whole genome mutagenesis. The method leverages an entirely random gRNA library and SpCas9-NG to randomly damage genomes in a controllable shotgun-like manner that then triggers diverse and abundant mutations via low-fidelity repair. As a proof-of-principle, CARM was applied to evolve the capacity of Saccharomyces cerevisiae BY4741 to produce {beta}-carotene. After seven rounds of iterative evolution over two months, a {beta}-carotene hyper-producing strain, C7-143, was isolated with a 10.5-fold increase in {beta}-carotene production and 857 diverse genomic mutants that comprised indels, duplications, inversions, and chromosomal rearrangements. Transcriptomic analysis revealed that the expression of 2,541 genes of strain C7-143 were significantly altered, suggesting that the metabolic landscape of the strain was deeply reconstructed. In addition, CARM was applied to evolve the industrially relevant Saccharomyces cerevisiae CEN.PK2-1C, the S-adenosyl-L-methionine production of which was increased to 2.28 times after just one round. Thus, CARM is a user-friendly and practical strategy for genetic remodeling and reverse engineering to investigate complicated organismal metabolism.

evolutionary biology↗

bioRxiv2021

Single cell RNA Sequencing Identifies G-protein Coupled Receptor 87 as a Novel Basal Cell Marker of Distal Honeycomb Cysts in Idiopathic Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a progressive and fatal lung disease with limited therapeutic options. Epithelial reprogramming and honeycomb cysts are key pathological features of IPF, however, the IPF distal bronchiole cell subtypes and their potential contribution to IPF development and progression still remain poorly characterized. Here, we utilized single-cell RNA sequencing on enriched EpCAM+ cells of the distal IPF and Donor lung. Using the 10x Genomics platform, we generated a dataset of 47,881 cells and found distinct cell clusters, including rare cell types, such as suprabasal cells recently reported in the healthy lung. We identified G-protein coupled receptor (GPR) 87 as a novel surface marker of distal Keratin (KRT)5+ basal cells. GPR87 expression was localized to distal bronchioles and honeycomb cysts in IPF in situ by RNA Scope and immunolabeling. Modulation of GPR87 in primary human bronchial epithelial cells cultures resulted in impaired airway differentiation and ciliogenesis. Thus, GPR87 is a novel marker and potentially druggable target of KRT5+ basal progenitor cells likely contributing to bronchiole remodeling and honeycomb cyst development in IPF.

cell biology↗