Bacteriophages are the most abundant biological entity in the biosphere. They facilitate the evolution of bacterial pathogenicity by imposing selection for resistance to infection and by horizontal gene transfer of host genes to new bacteria. More specifically, phages often carry toxins and virulence factors that convert benign bacteria into human pathogens, facilitating the spread of bacterial infections. Most phages utilize elaborate tail machines to translocate their viral DNA and proteins, across bacterial membranes, into a host cell. In addition, these highly sophisticated molecular machines are responsible for host-cell recognition, attachment, and cell wall penetration. However, initial adsorption and genome ejection remain the least understood aspects of any phage life cycle. The central hypothesis is that the tail machine undergoes a cascade of coordinated conformational changes to efficiently infect a host bacterium. The objective of this application is to document these conformational rearrangements by determining intermediate structures of Podoviridae T7, Myoviridae T4, and Siphoviridae ? during infection by combining high throughput cryo-electron tomography (cryo- ET) with molecular genetics of both phage and host. Comparative structural analysis of these three morphotypes, together with a wealth of biochemical and structural information, will provide new insights into the mechanistic pathways of phage infection at a molecular level.
Virus-host interactions, which are fundamental processes of any viral infection, have profound impacts on microbial community, ecosystem function, and human health. We combine traditional genetic and molecular biology with cutting-edge imaging techniques to visualize bacteriophage infection process in 3D with unprecedented resolution. Our novel in vivo structural insights into viral infection and DNA translocation will have broad implications on nanotechnology, antibacterial therapeutics, and the development of gene therapy delivery systems.
| Qin, Zhuan; Hu, Bo; Liu, Jun (2018) Visualizing Chemoreceptor Arrays in Bacterial Minicells by Cryo-Electron Tomography and Subtomogram Analysis. Methods Mol Biol 1729:187-199 |
| Tu, Jiagang; Park, Taehyun; Morado, Dustin R et al. (2017) Dual host specificity of phage SP6 is facilitated by tailspike rotation. Virology 507:206-215 |
| Farley, Madeline M; Tu, Jiagang; Kearns, Daniel B et al. (2017) Ultrastructural analysis of bacteriophage ?29 during infection of Bacillus subtilis. J Struct Biol 197:163-171 |
| Farley, Madeline M; Hu, Bo; Margolin, William et al. (2016) Minicells, Back in Fashion. J Bacteriol 198:1186-95 |
| Morado, Dustin R; Hu, Bo; Liu, Jun (2016) Using Tomoauto: A Protocol for High-throughput Automated Cryo-electron Tomography. J Vis Exp :e53608 |
| Hu, Bo; Margolin, William; Molineux, Ian J et al. (2015) Structural remodeling of bacteriophage T4 and host membranes during infection initiation. Proc Natl Acad Sci U S A 112:E4919-28 |
| Hu, Bo; Morado, Dustin R; Margolin, William et al. (2015) Visualization of the type III secretion sorting platform of Shigella flexneri. Proc Natl Acad Sci U S A 112:1047-52 |
| Hu, Bo; Margolin, William; Molineux, Ian J et al. (2013) The bacteriophage t7 virion undergoes extensive structural remodeling during infection. Science 339:576-9 |
