The mechanism of DNA ejection in the Bacillus anthracis spore-binding phage 8a revealed by cryo-electron tomography.
The structure of the Bacillus anthracis spore-binding phage 8a was determined by cryo-electron tomography. The phage capsid forms a T=16 icosahedron attached to a contractile tail via a head-tail connector protein. The tail consists of a six-start helical sheath surrounding a central tail tube, and a structurally novel baseplate at the distal end of the tail that recognizes and attaches to host cells. The parameters of the icosahedral capsid lattice and the helical tail sheath suggest protein folds for the capsid and tail-sheath proteins, respectively, and indicate evolutionary relationships to other dsDNA viruses. Analysis of 2518 intact phage particles show four distinct conformations that likely correspond to four sequential states of the DNA ejection process during infection. Comparison of the four observed conformations suggests a mechanism for DNA ejection, including the molecular basis underlying coordination of tail sheath contraction and genome release from the capsid.
Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030, USA.
Xiaofeng
X
Fu
Michael H
MH
Walter
Angel
A
Paredes
Marc C
MC
Morais
Jun
J
Liu
D017103:Bacillus Phages / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D001408:Bacillus anthracis / Q000821:virology; D002213:Capsid / Q000648:ultrastructure; D036022:Capsid Proteins / Q000737:chemistry / Q000648:ultrastructure; D004279:DNA, Viral / Q000378:metabolism*; D055032:Electron Microscope Tomography; D017900:Myoviridae / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D013171:Spores, Bacterial / Q000821:virology; D017376:Viral Tail Proteins / Q000737:chemistry / Q000648:ultrastructure
D036022:Capsid Proteins; D004279:DNA, Viral; D017376:Viral Tail Proteins