1. Lam
Emmett
Lisal
Kainov
Tuma
FSU
This virus is activated by single-stranded RNA entering through a pore.

10. The inner pore consists of a hexamer (34 kDa each) ATPase that powers the "motor" that propels the RNA through the pore. 

13. The structure of the pore hexamer protein (P4) assembly is known (at least for a homologous virus) from x-ray analysis

14. 5’ P4 P1

16. Translocation direction
Orientation of P4 within its Procapsid
Translocation direction
Capsid Interior

21. Orientation of P4 within its Procapsid
Translocation direction
Capsid Interior
However which end of the pore faces the outside was not known

22. P4 Alone P4 in Procapsid H/D Exchange Rate < 0.1 h-1
0.1 h h-1
1 h h-1
10 h h-1
> 100 h-1
P4 Alone
P4 in Procapsid

23. H/D Exchange Rate Study
Apical domain
P4 Alone
C-terminus
> 100 h-1
P4 in Procapsid
1 h h-1
10 h h-1
The C-terminus loses some solvent accessibility on binding to the virus.

24. The next question is, how does RNA squeeze through the pore on addition of ATP?
H/D exchange studies were performed on the pore hexamer:
in the free state
in the presence of ATP
in the presence of RNA
in the presence of both ATP and RNA

25. The affected peptide resides in the hydrophobic core

26. Mechanism of RNA loading during the initiation of packaging involves RNA-induced ring opening Surprisingly, RNA does not pry open the pore to make it wider. Rather the RNA squeezes between adjacent protein aceous monomeric components of the hexamer and then threads through the central hole.