The Enterovirus 71 A-particle Forms a Gateway to Allow Genome Release: A CryoEM Study of Picornavirus Uncoating
Figure 5
The two-fold axis of symmetry is wider in the A-particle than in the empty.
(A,B) Fitting of the EV71 procapsid crystal structure (3VBU, dark blue) [30], into the 6.3 Å A-particle cryo-EM map (A) and empty capsid (B) (rendered in grey mesh at 1σ ). Val 58 of VP2 (shown in red) is outside the density in both fittings. Lys 52 and Thr 54 of VP2 (shown in cyan) are within the density of the empty capsid, but protrude from the density in the A-particle fit. Side chains in this region that are within the density of both fitted structures are shown in dark blue. (C) The 8.7 Å EV71 A-particle map has enlarged openings at the two-fold axis of symmetry that measure 9.9 Å in diameter, indicating that these channels are larger in the A-particle and not an artifact due to the higher quality of the 6.3 Å A-particle map. (D) The EV71 empty capsid has openings at the two-fold axis of symmetry 7.1 Å in diameter, consistent with the procapsid crystal structure.