Jun Liu
Yale University, CT·Microbiology & Immunology
Bacteria and the viruses that infect them rely on tiny protein machines to swim, to inject proteins into host cells, and to push DNA across membranes. These machines drive how many germs cause disease, yet they are hard to see because they only work while embedded in a living cell.
- Fields
Microbiology & Immunology
Biophysics
Biochemistry
- Topics
cryo-electron tomography
cryo-ET
cryo-electron microscopy
- Grants
- 4 known grants, through Apr 2031
What they work on
- Dissect how the spoke-ring-cage protein network of the Helicobacter pylori sheathed flagellum assembles and enables optimal motility, using cryo-electron tomography with genetic and biochemical approaches.
- Determine how outer-membrane accessory proteins remodel membrane to form the flagellar sheath, and how sheathed flagella assemble while evading the host immune system.
- Determine the assembly pathway and structure of the Dot/Icm type IVB secretion machine of Legionella pneumophila and Coxiella burnetii, which delivers over 300 proteins into host cells, using cryo-ET plus genetics.
- Test how cytosolic ATPases recruit effector proteins and reshape the Dot/Icm machine, and characterize the translocation pore that forms the protein-conducting channel in the host cell membrane.
- Dissect the structure and function of the bacteriophage T7 genome ejection machine and determine how its extended tail spans the bacterial cell envelope.
- Illuminate how phage T7 adsorbs to a susceptible cell and recruits the host F1FO ATP synthase, the cell's rotary energy-producing enzyme, at the initiation of infection.
- Define the structure and function of the flagellar type III secretion apparatus in the Lyme disease spirochete Borrelia burgdorferi, using cryo-ET on a library of about 60 flagellar and chemotaxis mutants.
- Determine how the spirochetal periplasmic flagellar motor is driven by the proton motive force and how it switches rotational direction to control motility and chemotaxis.
More about the research
The central tool here is cryo-electron tomography (cryo-ET), which builds three-dimensional images of flash-frozen cells and reveals such machines in their native setting. Paired with genetics and biochemistry, this lets the lab assign a job to each protein part. Four projects apply this approach to flagella (the whip-like propellers bacteria rotate to swim), to a secretion machine that pumps proteins into host cells, and to the tail a bacterial virus uses to inject its genome.
Why it matters
Motility and protein-injection machines are what let these bacteria infect and persist, so mapping them points to new drug targets. Blocking the sheathed flagellum of Helicobacter pylori could interfere with a bacterium tied to ulcers and gastric cancer, and similar strategies could target the spirochetes behind syphilis, Lyme disease and leptospirosis. Work on the Dot/Icm machine of Legionella and Coxiella and on phage DNA delivery may also inform antibacterial therapeutics and nanotechnology.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Maria Lara-Tejero
Yale University, CT·Microbiology & Immunology
Determine the structure of the Salmonella type III secretion sorting platform, the part of the injectisome inside the bacterium, using cryo-EM and cryo-electron tomography.
Jorge E Galan
Yale University, CT·Microbiology & Immunology
Determine how short N-terminal secretion signals and dedicated chaperones direct client proteins to the type III secretion injectisome, the syringe-like machine Salmonella uses to inject proteins into host cells.
Nicholas Shikuma
San Diego State University, CA·Microbiology & Immunology
Identify and functionally test NF-κB homologs needed for bacteria-induced metamorphosis in the tubeworm Hydroides elegans, using RNA interference and gene expression analysis.
The school
Yale University: 73 labs on PI Pages, $1.5B a year on research, 438 research doctorates a year.
Reach out
A start for your email. Fill in the brackets.