Biology subjects

Olson, W. C.

Publications and source records attributed to Olson, W. C..

4 recordsLinked to original sources

bioRxiv2024

Structural characterization of two full length γδTCR/CD3 complexes

The T-cell receptor (TCR)/CD3 complex plays an essential role in the immune response and is a key player in cancer immunotherapies. There are two classes of TCR/CD3 complexes, defined by their TCR chain usage ({beta} or {gamma}{delta}). Recently reported structures have revealed the organization of the {beta} TCR/CD3 complex, but similar studies regarding the {gamma}{delta} TCR/CD3 complex have lagged behind. Here, we report cryoelectron microscopy (cryoEM) structural analysis of two full-length {gamma}{delta} TCRs, G115 (V{gamma}9V{delta}2) and 9C2 (V{gamma}5V{delta}1), in complex with CD3 subunits. Our results show that the overall subunit organization of the {gamma}{delta} TCR-CD3 complexes is similar to {beta} TCRs. However, both {gamma}{delta} TCRs display highly mobile extracellular domains (ECDs), unlike {beta} TCRs, which have TCR ECDs that are rigidly coupled to its transmembrane (TM) domains. We corroborate this finding in cells by demonstrating that a {gamma}{delta} T-cell specific antibody can bind a site that would be inaccessible in the more rigid {beta} TCR/CD3 complex. Furthermore, we observed that a V{gamma}5V{delta}1 complex forms a TCR {gamma}5-chain mediated dimeric species whereby two TCR/CD3 complexes are assembled. Collectively, these data shed light on {gamma}{delta} TCR/CD3 complex formation and may aid the design of {gamma}{delta} TCR-based therapies.

biochemistry↗

bioRxiv2024

Structural insights into CXCR4 modulation and oligomerization

Activation of the chemokine receptor CXCR4 by its chemokine ligand CXCL12 regulates diverse cellular processes. CXCR4 also serves as a key target for diseases such as cancer and HIV. Previously reported crystal structures of CXCR4 bound to antagonists revealed the architecture of an inactive, homodimeric receptor. However, many structural aspects of CXCR4 remain poorly understood, including its activation by CXCL12, as well as its assembly into higher-order oligomers. Here, we use cryoelectron microscopy (cryoEM) to investigate various modes of CXCR4 regulation in the presence and absence of Gi protein. CXCL12 activates CXCR4 by inserting its N-terminus deep into the CXCR4 orthosteric pocket. The binding of FDA-approved antagonist AMD3100 is stabilized by electrostatic interactions with acidic residues in the 7 transmembrane helix bundle. A potent antibody blocker, REGN7663, binds across the extracellular face of CXCR4 and inserts its CDR-H3 loop into the orthosteric pocket. Trimeric and tetrameric structures of CXCR4 reveal, to our knowledge, previously undescribed modes of GPCR oligomerization. Remarkably, CXCR4 adopts distinct subunit conformations in trimeric and tetrameric assemblies, highlighting how oligomerization could allosterically regulate chemokine receptor function.

biochemistry↗

bioRxiv2022

Structural analysis of cancer-relevant TCR-CD3 and peptide-MHC complexes by cryoEM

The recognition of antigenic peptide-MHC (pMHC) molecules by T-cell receptors (TCR) initiates the T-cell mediated immune response. Structural characterization is key for understanding the specificity of TCR-pMHC interactions and informing the development of therapeutics. Despite the rapid rise of single particle cryoelectron microscopy (cryoEM), x-ray crystallography has remained the preferred method for structure determination of TCR-pMHC complexes. Here, we report cryoEM structures of two distinct full-length /{beta} TCR-CD3 complexes bound to their pMHC ligand, the cancer-testis antigen HLA-A2/MAGEA4 (230-239). We also determined cryoEM structures of pMHCs containing MAGEA4 (230-239) peptide and the closely related MAGEA8 (232-241) peptide in the absence of TCR, which provided a structural explanation for the MAGEA4 preference displayed by the TCRs. These findings provide insights into the TCR recognition of a clinically relevant cancer antigen and demonstrate the utility of cryoEM for high-resolution structural analysis of TCR-pMHC interactions.

biochemistry↗

bioRxiv2022

Structural insights into the assembly of gp130 family cytokine signaling complexes

The gp130 family cytokine signaling complexes have limited structural information despite their crucial roles in various cellular processes. We determined cryo-EM structures of several complexes of this family, containing full ectodomains of both signaling receptors bound to their respective ligands CNTF, CLCF1, LIF, IL-27, and IL-6. Our structures reveal that gp130 serves as a central receptor by engaging Site 2 of CNTF, CLCF1, LIF, and IL-6, and Site 3 of IL-27 and IL-6. The acute bends at both signaling receptors in all complexes bring the membrane-proximal domains to a ~30 [A] range but with distinct distances and orientations, which might determine biological specificities of these cytokines. We also reveal how CLCF1 engages its secretion chaperone CRLF1. Our data provide valuable insights for therapeutically targeting gp130-mediated signaling.

biochemistry↗