Research

Major Research Experiences

1. Structural Diversity of Mammalian Motile Cilia

• Developed a novel protocol for isolating swine ependymal and bovine oviduct cilia.
• Used single-particle cryo-EM to resolve high-resolution structures of mammalian motile cilia doublet microtubules.
• Uncovered structural diversity across mammalian axonemes.

Figure 1. AI-assisted protein identification workflow.

2. Human endogenous retrovirus K (HERV-K) envelope structures in pre- and post-fusion

• First Structural Characterization
  This study reports the first high-resolution cryo-EM structures of the HERV-K envelope (Env) glycoprotein in both pre-fusion (2.2 Å) and post-fusion (2.8 Å) conformations.

• Novel Monoclonal Antibodies
  A panel of ten novel monoclonal antibodies was developed and characterized to recognize distinct subunits and conformational states of HERV-K Env. Two antibodies, Kenv-6 and Kenv-4, facilitated structure determination.

• Pre-fusion Env Architecture
  The pre-fusion Env is an elongated trimer with SU subunits forming an inverted tripod and TM subunits forming a clasp underneath. This structure is distinct from all known retroviral Env structures.

• Engineering a Stable Pre-fusion Trimer
  Successful stabilization of the metastable pre-fusion Env trimer was achieved using structure-guided mutations: a disulfide bond, furin site modification, and trimerization domain fusion.

• Unique TM Features in Post-fusion State
  The post-fusion TM forms a typical six-helix bundle but includes a unique “tether helix” not observed in other retroviral Envs, indicating structural divergence.

• SU Fold is Unique Among Retroviruses
  The SU subunit adopts a novel fold with a β-sheet-rich architecture, showing no structural homology to HIV-1, SIV, or Syncytin-2 SU, except for a conserved β-sheet in the base domain.

• Antibody Epitope Mapping
  Kenv-6 binds a conserved, conformational epitope at the SU apex, while Kenv-4 recognizes a post-fusion TM epitope spanning two protomers. These mAbs are valuable tools for detecting native Env.

• Biological and Therapeutic Relevance
  HERV-K Env is aberrantly expressed in various cancers and autoimmune diseases. The described structures and antibodies provide a foundation for developing diagnostics and immunotherapies.

• Glycan Shield Analysis
  Env carries 10 N-glycans per monomer, providing moderate shielding (31% on SU, 57% on TM). It is less shielded than HIV-1 Env, potentially exposing vulnerable epitopes for immune targeting.

• Implications for Disease and Therapy
  Findings suggest the structural basis for HERV-K Env’s role in disease and highlight its potential as a therapeutic target for cancer and autoimmune conditions.

Figure 2. HERV integration timeline.

Figure 3. Antibody assisted structure determination of HERV-K env in pre- and post- fusion conformations.

3. 3D Molecular Architecture of CAR T Cell Immune Synapses Revealed by Cryo-ET

• Investigated immune synapse formation between CAR T cells and cancer cells using cryo-electron tomography.
• Revealed key structural features enhancing our understanding of CAR T cell-mediated cytotoxicity.

4. Tulane Virus Structure and Receptor Switch

• Studied a novel Tulane virus variant with abolished receptor binding due to minor capsid protein mutations.
• Developed an innovative virus purification method, significantly enhancing yield and purity.
• Resolved the structure of the variant at 2.6 Å, revealing the structural basis for the receptor switch.

Figure 3. Model of receptor switching in Tulane virus.

5. Method Development in Single-Particle Cryo-EM

• Developed a web app for real-space helical indexing, enabling easy and reliable determination of helical parameters. Check out HI3D.
• Addressed air-water interface challenges by using encapsulin-based encaging.
• Optimized data collection strategies for the Volta phase plate to improve efficiency.