Efficient in vivo and in vitro assembly of retroviral capsids from Gag precursor proteins expressed in bacteria.
The capsid precursor protein (Gag) of Mason-Pfizer monkey virus, the prototype type D retrovirus, has been expressed to high levels in bacteria under the control of the phage T7 promoter. Electron microscopic studies of induced cells revealed the assembly of capsid-like structures within inclusion bodies that formed at the poles of the cells 6 h after induction with isopropyl-beta-D-thiogalactopyranoside (IPTG). The inclusion bodies and enclosed capsid-like structures were solubilized completely in 8 M urea, but following renaturation, we observed assembly in vitro of capsid-like structures that demonstrated apparent icosahedral symmetry. These results demonstrate for the first time that retroviral capsid precursors have the propensity to self-assemble in vitro and point to new approaches for the analysis of retroviral assembly and structure.
Klikova
M
M
Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague, Czech Republic.
Rhee
S S
SS
Hunter
E
E
Ruml
T
T
D002213:Capsid / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000648:ultrastructure; D015683:Gene Products, gag / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007181:Inclusion Bodies, Viral; D016093:Mason-Pfizer monkey virus / Q000378:metabolism* / Q000648:ultrastructure; D011498:Protein Precursors / Q000378:metabolism*
D015683:Gene Products, gag; D011498:Protein Precursors