Biology subjects

Yeh, J.

Publications and source records attributed to Yeh, J..

3 recordsLinked to original sources

bioRxiv2025

LetA defines a structurally distinct transporter family involved in lipid trafficking

Membrane transport proteins translocate diverse cargos, ranging from small sugars to entire proteins, across cellular membranes. A few structurally distinct protein families have been described that account for most of the known membrane transport processes. However, many membrane proteins with predicted transporter functions remain uncharacterized. We determined the structure of E. coli LetAB, a phospholipid transporter involved in outer membrane integrity, and found that LetA adopts a distinct architecture that is structurally and evolutionarily unrelated to known transporter families. LetA functions as a pump at one end of a ~225 [A] long tunnel formed by its binding partner, MCE protein LetB, creating a pathway for lipid transport between the inner and outer membranes. Unexpectedly, the LetA transmembrane domains adopt a fold that is evolutionarily related to the eukaryotic tetraspanin family of membrane proteins, including TARPs and claudins. LetA has no detectable homology to known transport proteins, and defines a new class of membrane transporters. Through a combination of deep mutational scanning, molecular dynamics simulations, AlphaFold-predicted alternative states, and functional studies, we present a model for how the LetA-like family of membrane transporters may use energy from the proton-motive force to drive the transport of lipids across the bacterial cell envelope.

biophysics↗

bioRxiv2024

Temporal and Spatial Characterization of CUL3KLHL20-driven Targeted Degradation of BET family, BRD Proteins by the Macrocycle-based Degrader BTR2004

Targeted protein degradation (TPD) is a promising new therapeutic modality that leverages the endogenous cellular protein degradation machinery of the ubiquitin-proteasome system (UPS) to degrade selected proteins. Recently, we developed a synthetic macrocycle ligand to recruit CUL3KLHL20 E3 ligase for TPD. Using this KLHL20 ligand, we constructed the PROTAC BTR2004, which demonstrated potent degradation of BET family proteins BRD 2, 3, and 4. As the TPD field expands, it is important to understand the cellular and biochemical properties of all utilized E3 ligases. Herein we report the temporal and spatial processes of BTR2004-facilitated BET family protein degradation by KLHL20: The target protein degradation kinetics, BTR2004 intracellular activity half-life, and the onset of BTR2004 cell permeabilization. Employing proximity ligation and confocal microscopy techniques, we also illustrate the subcellular location of the ternary complex assembly upon BTR2004 treatment. These characterizations provide further insight into the processes that govern TPD and features that could be incorporated when designing future PROTAC molecules.

biochemistry↗

bioRxiv2023

Plasma cells in human pancreatic ductal adenocarcinoma secrete antibodies to self-antigens

Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA sequencing (scRNA-Seq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from seven primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hyper-mutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissues, and observed frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein, RUVBL2, and the mitochondrial protein, HSPD1. Antibody titers to F-actin and HSPD1 were elevated in the plasma of PDAC patients, and also detectable in healthy donors. Thus, PCs in PDAC produce auto-antibodies reacting with intracellular self-antigens, which may result from promotion of pre-existing, autoreactive B cell responses. These observations indicate that the chronic inflammatory microenvironment of PDAC can support the adaptive immune response.

cancer biology↗