In vitro assembly of virus-like particles of a gammaretrovirus, the murine leukemia virus XMRV

Romana Hadravová, Alex de Marco, Pavel Ulbrich, Jitka Štokrová, Michal Doležal, Iva Pichová, Tomáš Ruml, John A.G. Briggs, Michaela Rumlová

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Immature retroviral particles are assembled by self-association of the structural polyprotein precursor Gag. During maturation the Gag polyprotein is proteolytically cleaved, yielding mature structural proteins, matrix (MA), capsid (CA), and nucleocapsid (NC), that reassemble into a mature viral particle. Proteolytic cleavage causes the N terminus of CA to fold back to form a β-hairpin, anchored by an internal salt bridge between the N-terminal proline and the inner aspartate. Using an in vitro assembly system of capsid-nucleocapsid protein (CANC), we studied the formation of virus-like particles (VLP) of a gammaretrovirus, the xenotropic murine leukemia virus (MLV)-related virus (XMRV). We show here that, unlike other retroviruses, XMRV CA and CANC do not assemble tubular particles characteristic of mature assembly. The prevention of β-hairpin formation by the deletion of either the N-terminal proline or 10 initial amino acids enabled the assembly of ΔProCANC or Δ10CANC into immature-like spherical particles. Detailed three-dimensional (3D) structural analysis of these particles revealed that below a disordered N-terminal CA layer, the C terminus of CA assembles a typical immature lattice, which is linked by rod-like densities with the RNP.

Original languageEnglish
Pages (from-to)1297-1306
Number of pages10
JournalJournal of Virology
Issue number3
Publication statusPublished - Feb 2012
Externally publishedYes

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