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.

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.