Binding mode-guided development of high-performance antibodies targeting site-specific posttranslational modifications.

Posttranslational modifications (PTMs) of proteins play critical roles in regulating many cellular events. Antibodies targeting site-specific PTMs are essential tools for detecting and enriching PTMs at sites of interest. However, fundamental difficulties in molecular recognition of both PTM and surrounding peptide sequence have hindered the efficient generation of highly sequence-specific anti-PTM antibodies.

Selective targeting of oncogenic hotspot mutations of the HER2 extracellular domain.

Oncogenic mutations in the extracellular domain (ECD) of cell-surface receptors could serve as tumor-specific antigens that are accessible to antibody therapeutics. Such mutations have been identified in receptor tyrosine kinases including HER2. However, it is challenging to selectively target a point mutant, while sparing the wild-type protein.

Cytosolic delivery of monobodies using the bacterial type III secretion system inhibits oncogenic BCR: ABL1 signaling.

Background: The inability of biologics to pass the plasma membrane prevents their development as therapeutics for intracellular targets. To address the lack of methods for cytosolic protein delivery, we used the type III secretion system (T3SS) of Y. enterocolitica, which naturally injects bacterial proteins into eukaryotic host cells, to deliver monobody proteins into cancer cells.

Proton-coupled transport mechanism of the efflux pump NorA.

Efflux pump antiporters confer drug resistance to bacteria by coupling proton import with the expulsion of antibiotics from the cytoplasm. Despite efforts there remains a lack of understanding as to how acid/base chemistry drives drug efflux. Here, we uncover the proton-coupling mechanism of the Staphylococcus aureus efflux pump NorA by elucidating structures in various protonation states of two essential acidic residues using cryo-EM.

Molecular basis for antibody recognition of multiple drug-peptide/MHC complexes.

The HapImmune platform exploits covalent inhibitors as haptens for creating major histocompatibility complex (MHC)-presented tumor-specific neoantigens by design, combining targeted therapies with immunotherapy for the treatment of drug-resistant cancers. A HapImmune antibody, R023, recognizes multiple sotorasib-conjugated KRAS(G12C) peptides presented by different human leukocyte antigens (HLAs). This high specificity to sotorasib, coupled with broad HLA-binding capability, enables such antibodies, when reformatted as T cell engagers, to potently and selectively kill sotorasib-resistant KRAS(G12C) cancer cells expressing different HLAs upon sotorasib treatment.

mRNA COVID-19 vaccine elicits potent adaptive immune response without the acute inflammation of SARS-CoV-2 infection.

SARS-CoV-2 infection and vaccination elicit potent immune responses. Our study presents a comprehensive multimodal single-cell analysis of blood from COVID-19 patients and healthy volunteers receiving the SARS-CoV-2 vaccine and booster. We profiled immune responses via transcriptional analysis and lymphocyte repertoire reconstruction.

β-Strand-mediated Domain-swapping in the Absence of Hydrophobic Core Repacking.

Domain swapping is a process wherein a portion of a protein is exchanged with its counterpart in another copy of the molecule, resulting in the formation of homo-oligomers with concomitant repacking of a hydrophobic core. Here, we report domain swapping triggered upon modifying a β-hairpin sequence within a single-layer β-sheet (SLB) of a model protein, OspA that did not involve the formation of a reorganized hydrophobic core. The replacement of two β-hairpin sequences with a Gly-Gly and shorteing of a β-hairpin resulted in a protein that formed two distinct crystal structures under similar conditions: one was monomeric, similar to the parental molecule, whereas the other was a domain-swapped dimer, mediated by an intermolecular β-sheet in the SLB portion.

The expression profile and tumorigenic mechanisms of CD97 (ADGRE5) in glioblastoma render it a targetable vulnerability.

Glioblastoma (GBM) is the most common and aggressive primary brain malignancy. Adhesion G protein-coupled receptors (aGPCRs) have attracted interest for their potential as treatment targets. Here, we show that CD97 (ADGRE5) is the most promising aGPCR target in GBM, by virtue of its de novo expression compared to healthy brain tissue.

Phosphorylation-dependent pseudokinase domain dimerization drives full-length MLKL oligomerization.

The necroptosis pathway is a lytic, pro-inflammatory mode of cell death that is widely implicated in human disease, including renal, pulmonary, gut and skin inflammatory pathologies. The precise mechanism of the terminal steps in the pathway, where the RIPK3 kinase phosphorylates and triggers a conformation change and oligomerization of the terminal pathway effector, MLKL, are only emerging. Here, we structurally identify RIPK3-mediated phosphorylation of the human MLKL activation loop as a cue for MLKL pseudokinase domain dimerization.

Tumor-intrinsic LKB1-LIF signaling axis establishes a myeloid niche to promote immune evasion and tumor growth.

Tumor mutations can influence the surrounding microenvironment leading to suppression of anti-tumor immune responses and thereby contributing to tumor progression and failure of cancer therapies. Here we use genetically engineered lung cancer mouse models and patient samples to dissect how mutations accelerate tumor growth by reshaping the immune microenvironment. Comprehensive immune profiling of -mutant vs wildtype tumors revealed dramatic changes in myeloid cells, specifically enrichment of Arg1 interstitial macrophages and SiglecF neutrophils.

Exploring switch II pocket conformation of KRAS(G12D) with mutant-selective monobody inhibitors.

The G12D mutation is among the most common KRAS mutations associated with cancer, in particular, pancreatic cancer. Here, we have developed monobodies, small synthetic binding proteins, that are selective to KRAS(G12D) over KRAS(wild type) and other oncogenic KRAS mutations, as well as over the G12D mutation in HRAS and NRAS. Crystallographic studies revealed that, similar to other KRAS mutant-selective inhibitors, the initial monobody bound to the S-II pocket, the groove between switch II and α3 helix, and captured this pocket in the most widely open form reported to date.

Use of Phage Display and Other Molecular Display Methods for the Development of Monobodies.

Synthetic binding proteins are human-made binding proteins that use non-antibody proteins as the starting scaffold. Molecular display technologies, such as phage display, enable the construction of large combinatorial libraries and their efficient sorting and, thus, are crucial for the development of synthetic binding proteins. Monobodies are the founding system of a set of synthetic binding proteins based on the fibronectin type III (FN3) domain.

Monobody Inhibitor Selective to the Phosphatase Domain of SHP2 and its Use as a Probe for Quantifying SHP2 Allosteric Regulation.

SHP2 is a phosphatase/adaptor protein that plays an important role in various signaling pathways. Its mutations are associated with cancers and developmental diseases. SHP2 contains a protein tyrosine phosphatase (PTP) and two SH2 domains.

Mutations in the α4-α5 allosteric lobe of RAS do not significantly impair RAS signaling or self-association.

Mutations in one of the three RAS genes (HRAS, KRAS, and NRAS) are present in nearly 20% of all human cancers. These mutations shift RAS to the GTP-loaded active state due to impairment in the intrinsic GTPase activity and disruption of GAP-mediated GTP hydrolysis, resulting in constitutive activation of effectors such as RAF. Because activation of RAF involves dimerization, RAS dimerization has been proposed as an important step in RAS-mediated activation of effectors.

Inhibition of RAS-driven signaling and tumorigenesis with a pan-RAS monobody targeting the Switch I/II pocket.

RAS mutants are major therapeutic targets in oncology with few efficacious direct inhibitors available. The identification of a shallow pocket near the Switch II region on RAS has led to the development of small-molecule drugs that target this site and inhibit KRAS(G12C) and KRAS(G12D). To discover other regions on RAS that may be targeted for inhibition, we have employed small synthetic binding proteins termed monobodies that have a strong propensity to bind to functional sites on a target protein.

Creating MHC-Restricted Neoantigens with Covalent Inhibitors That Can Be Targeted by Immune Therapy.

Unlabelled: Intracellular oncoproteins can be inhibited with targeted therapy, but responses are not durable. Immune therapies can be curative, but most oncogene-driven tumors are unresponsive to these agents. Fragments of intracellular oncoproteins can act as neoantigens presented by the major histocompatibility complex (MHC), but recognizing minimal differences between oncoproteins and their normal counterparts is challenging.

A Rapid and Sensitive Microfluidics-Based Tool for Seroprevalence Immunity Assessment of COVID-19 and Vaccination-Induced Humoral Antibody Response at the Point of Care.

As of 8 August 2022, SARS-CoV-2, the causative agent of COVID-19, has infected over 585 million people and resulted in more than 6.42 million deaths worldwide. While approved SARS-CoV-2 spike (S) protein-based vaccines induce robust seroconversion in most individuals, dramatically reducing disease severity and the risk of hospitalization, poorer responses are observed in aged, immunocompromised individuals and patients with certain pre-existing health conditions.

Engineering Binders with Exceptional Selectivity.

Molecular display technologies have enabled the generation of synthetic binders with high affinities against a variety of antigens. However, engineering binders with high selectivity is still a challenging task. Here, we illustrate points to consider in developing highly selective binders against antigens of interest.

Structural basis for inhibition of the drug efflux pump NorA from Staphylococcus aureus.

Membrane protein efflux pumps confer antibiotic resistance by extruding structurally distinct compounds and lowering their intracellular concentration. Yet, there are no clinically approved drugs to inhibit efflux pumps, which would potentiate the efficacy of existing antibiotics rendered ineffective by drug efflux. Here we identified synthetic antigen-binding fragments (Fabs) that inhibit the quinolone transporter NorA from methicillin-resistant Staphylococcus aureus (MRSA).