Structure of a headful DNA-packaging bacterial virus at 2.9 Å resolution by electron cryo-microscopy.
The enormous prevalence of tailed DNA bacteriophages on this planet is enabled by highly efficient self-assembly of hundreds of protein subunits into highly stable capsids. These capsids can stand with an internal pressure as high as ∼50 atmospheres as a result of the phage DNA-packaging process. Here we report the complete atomic model of the headful DNA-packaging bacteriophage Sf6 at 2.9 Å resolution determined by electron cryo-microscopy. The structure reveals the DNA-inflated, tensed state of a robust protein shell assembled via noncovalent interactions. Remarkable global conformational polymorphism of capsid proteins, a network formed by extended N arms, mortise-and-tenon-like intercapsomer joints, and abundant β-sheet-like mainchain:mainchain intermolecular interactions, confers significant strength yet also flexibility required for capsid assembly and DNA packaging. Differential formations of the hexon and penton are mediated by a drastic α-helix-to-β-strand structural transition. The assembly scheme revealed here may be common among tailed DNA phages and herpesviruses.
Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045.
Haiyan
H
Zhao
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
Kunpeng
K
Li
Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045.
Anna Y
AY
Lynn
Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045.
Keith E
KE
Aron
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
Guimei
G
Yu
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907 jiang12@purdue.edu tangl@ku.edu.
Wen
W
Jiang
Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045; jiang12@purdue.edu tangl@ku.edu.
Liang
L
Tang
D001435:Bacteriophages / Q000502:physiology*; D002213:Capsid / Q000737:chemistry*; D036022:Capsid Proteins / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D042003:DNA Packaging; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D019065:Virus Assembly
D036022:Capsid Proteins
DNA packaging; atomic structure; bacteriophage; cryoEM; virus assembly