Protein P7 of the cystovirus φ6 is located at the three-fold axis of the unexpanded procapsid.
The objective of this study was to determine the location of protein P7, the RNA packaging factor, in the procapsid of the φ6 cystovirus. A comparison of cryo-electron microscopy high-resolution single particle reconstructions of the φ6 complete unexpanded procapsid, the protein P2-minus procapsid (P2 is the RNA directed RNA-polymerase), and the P7-minus procapsid, show that prior to RNA packaging the P7 protein is located near the three-fold axis of symmetry. Difference maps highlight the precise position of P7 and demonstrate that in P7-minus particles the P2 proteins are less localized with reduced densities at the three-fold axes. We propose that P7 performs the mechanical function of stabilizing P2 on the inner protein P1 shell which ensures that entering viral single-stranded RNA is replicated.
Sophie Davis School of Biomedical Education, City College of New York, New York, New York, United States of America.
Garrett
G
Katz
Hui
H
Wei
Alexandra
A
Alimova
Al
A
Katz
David Gene
DG
Morgan
Paul
P
Gottlieb
D017126:Bacteriophage phi 6 / Q000235:genetics / Q000648:ultrastructure*; D002213:Capsid / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D012330:RNA, Double-Stranded / Q000737:chemistry; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D014764:Viral Proteins / Q000737:chemistry*; D019065:Virus Assembly; D014779:Virus Replication / Q000235:genetics*
D012330:RNA, Double-Stranded; D012367:RNA, Viral; D014764:Viral Proteins