Alkaline-triggered uncoating of Triatoma virus
(TrV) monitored
by native mass spectrometry. (a) Spectra of TrV virions, incubated
at different pHs. Signal corresponding to virion is highlighted in
red (m/z ∼40000; Mw ∼8.3
MDa), that of empty capsids in yellow (m/z ∼28000; Mw ∼5.4 MDa). (b) Model of the alkaline-triggered
uncoating of TrV. Under neutral pH, TrV confines a very large genome.
This comes at a high energetic cost, but the ssRNA stabilizes the
capsid, thereby preventing premature uncoating. At higher pH, this
stabilizing interaction is lost and electrostatic self-repulsion of
the ssRNA increases due to loss of charge on counterions; the capsid
bursts and falls apart into pentons. The genome and VP4 are released
into solution and pentons reassemble into empty capsids. Adapted by
permission from Macmillan Publishers Ltd.: Nat. Chem. Snijder, J.; Uetrecht, C.; Rose, R. J.; Sanchez-Eugenia, R.; Marti,
G. A. et al. 2013 Probing the biophysical interplay between
a viral genome and its capsid. Nat. Chem.5(6): 502–509 (ref (24)). Copyright 2013.