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Yingyuan Sun

Yingyuan Sun Profile Picture

Graduate Research Assistant

Contact Info:

Training Group(s):
Biomolecular Structure and Biophysics

Current Research Interests:

Structural changes during the viral entry of Bacteriophage phiX174

Tail-less bacteriophage phiX174 uses a tubular structure that consists of ten copies of H proteins to translocate its genome into the cytoplasmic space of host cells. It remains elusive how the H-tube is assembled and what roles G and F proteins play in the infection process. Lipopolysaccharides (LPS) were used to trigger ssDNA ejection from phiX174 so that we are able to study the conformational changes of the structural proteins during this process.

We have investigated the dynamic of the interaction between LPS and phiX174 particles with small-angle X-ray scattering. The results show a loss of symmetry and an increasing radius of gyration at the early stage of the reaction, which are caused by phiX174’s binding to LPS bilayers through one icosahedral vertex and the loss of genome respectively. Then cryo electron microscopy was used to determine the structures of phiX174 complexed with LPS. The maps indicate that the G spike at the vertex in contact with LPS has dissociated from the capsid, leaving the EF loop on F proteins maintaining the viral attachment. When comparing reconstructions of full and emptied phiX174 particles, we found that the HI loops of F proteins at the special vertex have undergone conformational changes and form an open channel which is presumably the exit for the ssDNA genome.

Selected Publications:

  • Student Profile

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