Biology subjects

Subramaniam, S.

Publications and source records attributed to Subramaniam, S..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Liver transplant rejection features memory cell priming, spatially differentiated networks and novel drug targets.

Acute T-cell-mediated transplant rejection, the earliest contributor to immunological graft failure responds variably to T-cell suppression. Early rejection can co-exist with donor-specific antibodies which also shorten graft survival, without affecting graft histology visibly. Here, during early liver transplant rejection, blood leukocytes manifest primed T-cells with heat shock protein (HSP) signaling and transcriptional programs for memory cell expansion. Corresponding biopsies demonstrate upregulated immune synapse and proteasomal genes in T-cell-infiltrated portal and central regions of the liver lobule. With donor-specific antibodies, the intervening intralobular region demonstrates a germinal-center-like allograft response with upregulated CD40, chemokine, T-follicular and complement signaling, which intensifies along the direction of sinusoidal blood flow from portal to central regions. Proteasomal and HSP90 inhibitors suppress donor-specific alloresponses of T- and B-cells in blood samples from patients with early rejection. The molecular injury spectrum of early rejection is complex, spatially differentiated and reveals novel early immunosuppressive strategies to extend graft survival.

immunology↗

bioRxiv2025

The CFDE Workbench: Integrating Metadata and Processed Data from Common Fund Programs

The NIH Common Fund Data Ecosystem (CFDE) program was established to facilitate data accessibility and interoperability across multiple Common Fund (CF) programs and promote collaborations and new discoveries by combining data from different CF programs. The CFDE Data Resource Center (DRC) was tasked with developing two web-based portals: an Information Portal to serve information about the CFDE, and a Data Portal to host harmonized metadata and processed data contributed by participating CF Data Coordination Centers (DCCs) and other sources. To achieve these goals, the CFDE DRC developed the CFDE Workbench, a web-based platform that hosts highly processed data, metadata, tools, use cases, and analyses developed by the CFDE. The Crosscut Metadata Model (C2M2) and several other processed data formats are hosted by the CFDE Workbench, including set libraries (XMTs), Knowledge Graph (KG) assertions, and attribute tables. These processed data formats make information derived from CF programs more findable, accessible, interoperable, and reusable (FAIR) and artificial intelligence (AI)-ready for cross-DCC knowledge discovery. In addition to these processed data formats, several other assets are served by the Workbench, including Extract Transform Load (ETL) pipelines, OpenAPI-documented and SmartAPI-registered Representational State Transfer (REST) Application Programming Interfaces (APIs), entity pages such as gene, drug, disease, or tissue landing pages, Playbook Workflow Builder (PWB) metanodes which are codified workflow steps involving DCC APIs, and chatbot specifications which are prompts helping chatbots to use DCC APIs to answer a wide range of user queries. Besides serving data, metadata, and code assets, the CFDE Workbench also has several tools that use these data, metadata, and code assets to enable cross-CF-program knowledge discovery use cases. Overall, the CFDE Workbench is a platform that consolidates efforts toward making CF programs funded resources harmonized, FAIR, and AI-ready. The CFDE Workbench website is available from: https://cfde.info/.

bioinformatics↗

bioRxiv2025

Tryptophan metabolism reprogramming contributes to the prothrombotic milieu in mice and humans infected with SARS-CoV-2

SARS-CoV-2 infection disturbs the coagulation balance in the blood, triggering thrombosis and contributing to organ failure. The role of prothrombotic metabolites in COVID-19-associated coagulopathy remains elusive. Leveraging K18-hACE2 mice infected with SARS-CoV-2, we observed higher levels of the tryptophan metabolite, kynurenine, compared to controls. SARS-CoV-2 infected mice showed a significant upregulation of enzymes controlling Kynurenine biogenesis, such as indoleamine 2,3-dioxygenase (IDO-1) and tryptophan 2,3-dioxygenase levels in kidneys and liver, respectively, as well as changes in the enzymes involved in kynurenine catabolism, including kynurenine monooxygenase and kynurinase. Consistent with the agonistic role of these metabolites in Aryl Hydrocarbon Receptor (AHR) signaling, AHR activation and its downstream mediator, tissue factor (TF), a highly potent procoagulant factor, was observed in endothelial cells (ECs) of lungs and kidneys of infected mice. These findings were validated in humans, where compared to controls, sera of COVID-19 patients showed increased levels of Kynurenine, kynurenic acid, anthranilic acid, and quinolinic acid. Activation of the AHR-TF axis was noted in the kidneys and lungs of COVID-19 patients, and COVID-19 sera showed higher IDO-1 activity than controls. Levels of Kyn in COVID-19 patients correlated strongly with the TF-inducing activity of COVID-19 sera on ECs. A specific IDO-1 inhibitor or AHR inhibitor separately or in combination suppressed COVID-19 sera-induced TF activity in ECs. Together, we identified IDO-1 as upregulated by SARS-CoV-2 infection, resulting in augmented Kyn and its prothrombotic catabolites, thereby suggesting the Kyn-AHR-TF axis as possibly a new diagnostic and/or therapeutic target. Key pointsO_LISARS-CoV-2-infection upregulates kynurenine biogenesis in the liver and diminishes kynurenine catabolism in the lungs and kidneys. C_LIO_LIAn increase in kynurenine stimulates the AHR-TF axis in the microvasculature in COVID-19 patients, which is inhibited by pharmacological manipulation. C_LI

systems biology↗

bioRxiv2024

M2 Macrophages are Major Mediators of Germline Risk of Endometriosis and Explain Pleiotropy with Comorbid Traits

Endometriosis is a common gynecologic condition that causes chronic life-altering symptoms including pain, infertility, and elevated cancer risk. There is an urgent need for new non-hormonal targeted therapeutics to treat endometriosis, but until very recently, the cellular and molecular signatures of endometriotic lesions were undefined, severely hindering the development of clinical advances. Integrating inherited risk data from analyses of >450,000 individuals with [~]350,000 single cell transcriptomes from 21 patients, we uncover M2-macrophages as candidate drivers of disease susceptibility, and nominate IL1 signaling as a central hub impacted by germline genetic variation associated with endometriosis. Extensive functional follow-up confirmed these associations and revealed a pleiotropic role for this pathway in endometriosis. Population-scale expression quantitative trail locus analysis demonstrated that genetic variation controlling IL1A expression is also associated with endometriosis risk variants. Manipulation of IL1 signaling in state-of-the-art in vitro decidualized assembloids impacted epithelial differentiation, and in an in vivo endometriosis model, treatment with anakinra (an interleukin-1 receptor antagonist) resulted in a significant, dose-dependent reduction in both spontaneous pain and evoked pain. Together these studies highlight non-diagnostic cell types as central to endometriosis susceptibility and support IL1 signaling as an important actionable pathway for this disease.

immunology↗

bioRxiv2024

The molecular chronology of mammary epithelial cell fate switching

The adult mammary gland is maintained by lineage-restricted progenitor cells through pregnancy, lactation, involution, and menopause. Injury resolution, transplantation-associated mammary gland reconstitution, and tumorigenesis are unique exceptions, wherein mammary basal cells gain the ability to reprogram to a luminal state. Here, we leverage newly developed cell-identity reporter mouse strains, and time-resolved single-cell epigenetic and transcriptomic analyses to decipher the molecular programs underlying basal-to-luminal fate switching in vivo. We demonstrate that basal cells rapidly reprogram toward plastic cycling intermediates that appear to hijack molecular programs we find in bipotent fetal mammary stem cells and puberty-associatiated cap cells. Loss of basal-cell specifiers early in dedifferentiation coincides with activation of Notch and BMP, among others. Pharmacologic blockade of each pathway disrupts basal-to-luminal transdifferentiation. Our studies provide a comprehensive map and resource for understanding the coordinated molecular changes enabling terminally differentiated epithelial cells to transition between cell lineages and highlights the stunning rapidity by which epigenetic reprogramming can occur in response to disruption of tissue structure.

cell biology↗

bioRxiv2024

Tumor suppressor NME1/NM23-H1 modulates DNA binding of NF-κB RelA

The dimeric NF-{kappa}B family of transcription factors activates transcription by binding sequence-specifically to DNA response elements known as {kappa}B sites, located within the promoters and enhancers of their target genes. While most NF-{kappa}B remain inactive in the cytoplasm of unstimulated cells, a small amount of RelA, one of its members, persists in the nucleus, ensuring low-level expression of genes essential for homeostasis. Several cofactors have been identified that aid in DNA binding of RelA. In this study, we identify NME1 (nucleoside diphosphate kinase 1) as a cofactor that enhances RelAs ability to bind {kappa}B sites within the promoters of a subset of its target genes, promoting their expression under both unstimulated and stimulated conditions. Depletion of NME1 influences activation or repression of several genes that are unresponsive to TNF, despite containing {kappa}B sites in their promoters but not in clusters. This suggests that clustering of kB sites may be necessary for RelA-dependent transcription complex assembly. NME1 appears to act as a cofactor for other transcription factors to regulate these genes. NME1 does not directly contact {kappa}B DNA but interacts with RelA, with this interaction being further strengthened in the presence of {kappa}B DNA. Notably, NME1 alone has a marginal effect in enhancing RelAs DNA binding, suggesting that NME1 likely cooperate with other cofactors to regulate DNA binding and transcription through RelA. These observations underscore the intricate assembly of transcription complexes centered on NF-{kappa}B.

biochemistry↗

bioRxiv2024

Playbook Workflow Builder: Interactive Construction of Bioinformatics Workflows from a Network of Microservices

Many biomedical research projects produce large-scale datasets that may serve as resources for the research community for hypothesis generation, facilitating diverse use cases. Towards the goal of developing infrastructure to support the findability, accessibility, interoperability, and reusability (FAIR) of biomedical digital objects and maximally extracting knowledge from data, complex queries that span across data and tools from multiple resources are currently not easily possible. By utilizing existing FAIR application programming interfaces (APIs) that serve knowledge from many repositories and bioinformatics tools, different types of complex queries and workflows can be created by using these APIs together. The Playbook Workflow Builder (PWB) is a web-based platform that facilitates interactive construction of workflows by enabling users to utilize an ever-growing network of input datasets, semantically annotated API endpoints, and data visualization tools contributed by an ecosystem. Via a user-friendly web-based user interface (UI), workflows can be constructed from contributed building-blocks without technical expertise. The output of each step of the workflows are provided in reports containing textual descriptions, as well as interactive and downloadable figures and tables. To demonstrate the ability of the PWB to generate meaningful hypotheses that draw knowledge from across multiple resources, we present several use cases. For example, one of these use cases sieves novel targets for individual cancer patients using data from the GTEx, LINCS, Metabolomics, GlyGen, and the ExRNA Communication Consortium (ERCC) Common Fund (CF) Data Coordination Centers (DCCs). The workflows created with the PWB can be published and repurposed to tackle similar use cases using different inputs. The PWB platform is available from: https://playbook-workflow-builder.cloud/.

bioinformatics↗

bioRxiv2023

The Arabidopsis Information Resource in 2024

Since 1999, The Arabidopsis Information Resource (www.arabidopsis.org) has been curating data about the Arabidopsis thaliana genome. Its primary focus is integrating experimental gene function information from the peer-reviewed literature and codifying it as controlled vocabulary annotations. Our goal is to produce a gold standard functional annotation set that reflects the current state of knowledge about the Arabidopsis genome. At the same time, the resource serves as a nexus for community-based collaborations aimed at improving data quality, access and reuse. For the past decade, our work has been made possible by subscriptions from our global user base. This update covers our ongoing biocuration work, some of our modernization efforts that contribute to the first major infrastructure overhaul since 2011, the introduction of JBrowse2, and the resources role in community activities such as organizing the structural reannotation of the genome. For gene function assessment, we used Gene Ontology annotations as a metric to evaluate: (1) what is currently known about Arabidopsis gene function, and (2) the set of unknown genes. Currently, 74% of the proteome has been annotated to at least one Gene Ontology term. Of those loci, half have experimental support for at least one of the following aspects: molecular function, biological process, or cellular component. Our work sheds light on the genes for which we have not yet identified any published experimental data and have no functional annotation. Drawing attention to these unknown genes highlights knowledge gaps and potential sources of novel discoveries. Article SummaryThe Arabidopsis Information Resource (TAIR, www.arabidopsis.org) is a comprehensive website about Arabidopsis thaliana, a small plant thats very easy to grow and analyze in the laboratory and is used to understand how many other plants function. We share our progress in data collection and organization, website and tool improvement, and our involvement in community projects.

plant biology↗

bioRxiv2023

Short oligomers rather than rings of human RAD52 promote single-strand annealing

Genome maintenance and stability rely on the repair of DNA double-strand breaks. The break repair can be mediated by the single-strand annealing protein RAD52. RAD52 forms rings that are thought to promote annealing. However, RAD52s annealing activity decreases with increasing concentrations that favor ring formation. Thus, which oligomeric form and how RAD52 anneals DNA strands and detects sequence homology is unclear. We combine mass photometry with biochemical assays to quantify oligomeric states of human RAD52 with and without DNA and put forward an alternative mechanism illustrating the critical role of short oligomers for single-stranded DNA annealing. We found that while truncated RAD52 formed undecameric rings at nanomolar concentrations, full-length RAD52 was mostly monomeric at lower nanomolar, physiological concentrations. At higher concentrations, it formed rings with a variable stoichiometry from heptamers to tridecamers. At low concentrations, with hardly any rings present, RAD52 already promoted single-strand annealing. Rings and short oligomers could bind at least two single DNA strands, but if complementary strands were both bound to rings annealing was inhibited. Our findings suggest that single-strand annealing and homology detection is mediated by short oligomers of RAD52 instead of rings.

molecular biology↗

bioRxiv2023

A bistable inhibitory OptoGPCR for multiplexed optogenetic control of neural circuits

Information is transmitted between brain regions through the release of neurotransmitters from long-range projecting axons. Understanding how the activity of such long-range connections contributes to behavior requires efficient methods for reversibly manipulating their function. Chemogenetic and optogenetic tools, acting through endogenous G-protein coupled receptor (GPCRs) pathways, can be used to modulate synaptic transmission, but existing tools are limited in sensitivity, spatiotemporal precision, or spectral multiplexing capabilities. Here we systematically evaluated multiple bistable opsins for optogenetic applications and found that the Platynereis dumerilii ciliary opsin (PdCO) is an efficient, versatile, light-activated bistable GPCR that can suppress synaptic transmission in mammalian neurons with high temporal precision in-vivo. PdCO has superior biophysical properties that enable spectral multiplexing with other optogenetic actuators and reporters. We demonstrate that PdCO can be used to conduct reversible loss-of-function experiments in long-range projections of behaving animals, thereby enabling detailed synapse-specific functional circuit mapping.

neuroscience↗

bioRxiv2023

Modeling transcriptional regulation of the cell cycle using a novel cybernetic-inspired approach

Quantitative understanding of cellular processes, such as cell cycle and differentiation, is impeded by various forms of complexity ranging from myriad molecular players and their multilevel regulatory interactions, cellular evolution with multiple intermediate stages, lack of elucidation of cause-effect relationships among the many system players, and the computational complexity associated with the profusion of variables and parameters. In this paper, we present an elegant modeling framework based on the cybernetic concept that biological regulation is inspired by objectives embedding entirely novel strategies for dimension reduction, process stage specification through the system dynamics, and innovative causal association of regulatory events with the ability to predict the evolution of the dynamical system. The elementary step of the modeling strategy involves stage-specific objective functions that are computationally-determined from experiments, augmented with dynamical network computations involving end point objective functions, mutual information, change point detection, and maximal clique centrality. We demonstrate the power of the method through application to the mammalian cell cycle, which involves thousands of biomolecules engaged in signaling, transcription, and regulation. Starting with a fine-grained transcriptional description obtained from RNA sequencing measurements, we develop an initial model, which is then dynamically modeled using the cybernetic-inspired method (CIM), utilizing the strategies described above. The CIM is able to distill the most significant interactions from a multitude of possibilities. In addition to capturing the complexity of regulatory processes in a mechanistically causal and stage-specific manner, we identify the functional network modules, including novel cell cycle stages. Our model is able to predict future cell cycles consistent with experimental measurements. We posit that this state-of-the-art framework has the promise to extend to the dynamics of other biological processes, with a potential to provide novel mechanistic insights. STATEMENT OF SIGNIFICANCECellular processes like cell cycle are overly complex, involving multiple players interacting at multiple levels, and explicit modeling of such systems is challenging. The availability of longitudinal RNA measurements provides an opportunity to "reverse-engineer" for novel regulatory models. We develop a novel framework, inspired using goal-oriented cybernetic model, to implicitly model transcriptional regulation by constraining the system using inferred temporal goals. A preliminary causal network based on information-theory is used as a starting point, and our framework is used to distill the network to temporally-based networks containing essential molecular players. The strength of this approach is its ability to dynamically model the RNA temporal measurements. The approach developed paves the way for inferring regulatory processes in many complex cellular processes.

systems biology↗

bioRxiv2022

Methadone alters transcriptional programs associated with synapse formation in human cortical organoids

Opioid use disorder (OUD) among pregnant women has become an epidemic in the United States. Pharmacological interventions for OUD involve methadone, a synthetic opioid analgesic that attenuates withdrawal symptoms and behaviors linked with maternal drug abuse. However, methadones ability to readily accumulate in neural tissue, and cause long-term neurocognitive sequelae, has led to concerns regarding its effect on prenatal brain development. We took advantage of human cortical organoid (hCO) technology to probe how this drug impacts the earliest mechanisms giving rise to the cerebral cortex. To this end, we conducted bulk mRNA sequencing of 2-month-old hCOs derived from two cell lines that were chronically treated with a clinically relevant dose of 1M methadone for 50 days. Differential expression and gene ontology analyses revealed a robust transcriptional response to methadone associated with functional components of the synapse, the underlying extracellular matrix (ECM), and cilia. Further unsupervised co-expression network and predictive protein-protein interaction analyses demonstrated that these changes occurred in concert, centered around a regulatory axis consisting of growth factors, developmental signaling pathways, and matricellular proteins. Our results demonstrate that exposure to methadone during early cortico-genesis fundamentally alters transcriptional programs associated with synapse formation, and that these changes arise by modulating extra-synaptic molecular mechanisms in the ECM and cilia. These findings provide novel insight into methadones putative effect on cognitive and behavioral development and a basis for improving interventions for maternal opioid addiction.

neuroscience↗

bioRxiv2022

Mapping molecular determinants of Cav2.2 inhibition by RGK proteins and homologs in Xenopus oocytes

The CaV1 and CaV2 families of voltage-dependent calcium channels play a crucial role in neurotransmitter release, excitation-contraction and many other cellular processes. Comprised of the membrane pore-forming 1, intracellular {beta} and extracellular 2{delta} subunits, these channels have been targets for pharmacological intervention for decades. Physiological functions of CaV channels are attenuated by either constitutively or transiently bounds proteins in the cellular environment. The RGK (Rad, Gem, Rem, and Rem2) G-protein family potently inhibits CaV1 and CaV2 function in heterologous expression systems. RGK proteins bind to CaV{beta} and inhibit channel localization and activity by forming a ternary complex with CaV1. Here, we evaluated the influence of RGK proteins on CaV2.2 channels heterologously expressed in Xenopus oocytes. Both Gem and Rad showed no nucleotide dependency on its inhibitory function on CaV2.2. The G-domain and C-terminus could inhibit the CaV2.2 channel independently when co-expressed with channel subunits. Our results demonstrated that structural determinants in Gem, crucial for channel inhibition, lie within the 222-296 amino acid region containing both the partial G-domain and C-terminus as determined from chimeric CaV{beta}-Gem constructs. We expanded our mapping efforts and prepared various chimeras of Drosophila melanogaster (Dm) RGK sequences fused to CaV{beta} and showed that 22 residues in RGK2t and RGK3L C-terminal imparted complete CaV2.2 inhibition. Point mutations in the DmRGK C-terminus, conserved in mammalian RGK proteins, abrogated the CaV2.2 inhibition to a significant extent, pointing to a hot region in the extreme C-terminus for inhibition of CaV channels. Since RGK homologs are now recognized as physiological modulators in {beta}-adrenergic regulation of CaV channels, the relevance of this curious G-protein family deserves close examination.

physiology↗

bioRxiv2022

Potent Neutralization of Omicron and other SARS-CoV-2 Variants of Concern by Biparatopic Human VH Domains

The emergence of SARS-CoV-2 variants of concern (VOCs) requires the development of next-generation biologics that are effective against a variety of strains of the virus. Herein, we characterize a human VH domain, F6, which we generated by sequentially panning large phage displayed VH libraries against receptor binding domains (RBDs) containing VOC mutations. Cryo-EM analyses reveal that F6 has a unique binding mode that spans a broad surface of the RBD and involves the antibody framework region. Attachment of an Fc region to a fusion of F6 and ab8, a previously characterized VH domain, resulted in a construct (F6-ab8-Fc) that neutralized Omicron pseudoviruses with a half-maximal neutralizing concentration (IC50) of 4.8 nM in vitro. Additionally, prophylactic treatment using F6-ab8-Fc reduced live Beta (B.1.351) variant viral titers in the lungs of a mouse model. Our results provide a new potential therapeutic against SARS-CoV-2 VOCs - including the recently emerged Omicron variant - and highlight a vulnerable epitope within the spike protein RBD that may be exploited to achieve broad protection against circulating variants.

immunology↗

bioRxiv2022

Whole-Genome Sequence of African Swine Fever Virus isolate from India provides insights into diversity and evolution

African swine fever (ASF) was first reported in 1921, and since then has posed a major threat to the world pig industry and still remains a major challenge as there is no vaccine or therapy available. In May 2020, the first incidence of ASF was recorded in India, followed by a number of outbreaks in the north eastern part of India. In this study, we report the first whole genome of an Indian isolate of ASF virus (ASF/IND/20/CAD/543) using next generation sequencing and compared with the other ASFV complete genome. On phylogenetic analysis, the virus was assigned to genotype II on the basis of p72 genotyping. However, the whole genome based phylogeny distinguished it from other genotype II isolates of clade 1.1.1. This study adds to our understanding of ASFVs genetic diversity and molecular evolution.

microbiology↗

bioRxiv2021

Coagulation Factor IIIa (f3a) Knockdown in Zebrafish Leads to Defective Angiogenesis and Mild Bleeding Phenotype

AimTissue factor (TF), an initiator of the extrinsic coagulation pathway, is crucial for embryogenesis, as mice lacking TF are embryonically lethal (E10.5). This lethality may be attributed to defects in vascular development and circulatory failure, suggesting additional roles for TF in embryonic development beyond coagulation. In this study, we characterized the role of one of the TF paralogs (f3a) using a zebrafish model. MethodsTo understand the TF evolution across different species, we performed molecular phylogenetic and sequence homology analysis. The expression of f3a during embryonic developmental stages was determined by RT-PCR. Endothelial-specific transgenic lines of zebrafish (flk1:egfp-NLS/kdrl:mCherry-CAAX) was used to image the vascular development. The role of f3a during embryonic development was investigated by mRNA knockdown using Morpholinos (MO), an antisense-based oligonucleotide strategy. The f3a morphants were examined at 52 hpf for defects in morphological appearance, bleeding, and vascular patterning. ResultsSpatiotemporal expression of f3a by qPCR revealed expression in all developmental stages, suggesting that f3a transcripts are both maternally and zygotically expressed. High expression of f3a from 28 hpf to 36 hpf confirmed the role of in the development of the yolk sac, circulation, and fins. f3a MO-injected embryos showed morphological abnormalities, including shorter body lengths and crooked tails. O-dianisidine staining showed f3a MO-injected embryos exhibited bleeding in the trunk (5.44%) and head (9.52%) regions. Using endothelial-specific transgenic lines of zebrafish (flk1:egfp-NLS/kdrl:mCherry-CAAX), imaging of caudal vein plexus, which forms immediately following the onset of circulation and sprouting, showed a 3-fold decrease in f3a morphants versus controls at 48 hpf, suggesting a potential role for f3a in flow-induced angiogenesis. Conclusionf3a is essential for angiogenesis, in addition to its involvement in hemostasis. Key PointsO_LIf3a knockdown by antisense morpholino oligonucleotide (MO)-approach shows bleeding phenotype. C_LIO_LIf3a is essential for angiogenesis, in addition to its involvement in hemostasis. C_LI

developmental biology↗

bioRxiv2021

SARS-CoV-2 Omicron Variant: ACE2 Binding, Cryo-EM Structure of Spike Protein-ACE2 Complex and Antibody Evasion

The newly reported Omicron variant is poised to replace Delta as the most rapidly spread SARS-CoV-2 variant across the world. Cryo-EM structural analysis of the Omicron variant spike protein in complex with human ACE2 reveals new salt bridges and hydrogen bonds formed by mutated residues R493, S496 and R498 in the RBD with ACE2. These interactions appear to compensate for other Omicron mutations such as K417N known to reduce ACE2 binding affinity, explaining our finding of similar biochemical ACE2 binding affinities for Delta and Omicron variants. Neutralization assays show that pseudoviruses displaying the Omicron spike protein exhibit increased antibody evasion, with greater evasion observed in sera obtained from unvaccinated convalescent patients as compared to doubly vaccinated individuals (8-vs 3-fold). The retention of strong interactions at the ACE2 interface and the increase in antibody evasion are molecular factors that likely contribute to the increased transmissibility of the Omicron variant.

biochemistry↗

bioRxiv2021

Emerging SARS-CoV-2 Variants of Concern: Spike Protein Mutational Analysis and Epitope for Broad Neutralization

Mutations in the spike glycoproteins of SARS-CoV-2 variants of concern have independently been shown to enhance aspects of spike protein fitness. Here, we report the discovery of a novel antibody fragment (VH ab6) that neutralizes all major variants, with a unique mode of binding revealed by cryo-EM studies. Further, we provide a comparative analysis of the mutational effects within variant spikes and identify the structural role of mutations within the NTD and RBD in evading antibody neutralization. Our analysis shows that the highly mutated Gamma N-terminal domain exhibits considerable structural rearrangements, partially explaining its decreased neutralization by convalescent sera. Our results provide mechanistic insights into the structural, functional, and antigenic consequences of SARS-CoV-2 spike mutations and highlight a spike protein vulnerability that may be exploited to achieve broad protection against circulating variants.

biochemistry↗