DNA poised for release in bacteriophage phi29.
We present here the first asymmetric, three-dimensional reconstruction of a tailed dsDNA virus, the mature bacteriophage phi29, at subnanometer resolution. This structure reveals the rich detail of the asymmetric interactions and conformational dynamics of the phi29 protein and DNA components, and provides novel insight into the mechanics of virus assembly. For example, the dodecameric head-tail connector protein undergoes significant rearrangement upon assembly into the virion. Specific interactions occur between the tightly packed dsDNA and the proteins of the head and tail. Of particular interest and novelty, an approximately 60A diameter toroid of dsDNA was observed in the connector-lower collar cavity. The extreme deformation that occurs over a small stretch of DNA is likely a consequence of the high pressure of the packaged genome. This toroid structure may help retain the DNA inside the capsid prior to its injection into the bacterial host.
Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA 92093, USA.
Jinghua
J
Tang
Norman
N
Olson
Paul J
PJ
Jardine
Shelley
S
Grimes
Dwight L
DL
Anderson
Timothy S
TS
Baker
D017103:Bacillus Phages / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D036022:Capsid Proteins / Q000737:chemistry* / Q000648:ultrastructure; D004279:DNA, Viral / Q000737:chemistry* / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D014771:Virion / Q000737:chemistry* / Q000648:ultrastructure; D019065:Virus Assembly
D036022:Capsid Proteins; D004279:DNA, Viral; C097975:portal protein, bacteriophage phi29