1u6p

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NMR Structure of the MLV encapsidation signal bound to the Nucleocapsid protein

Overview

All retroviruses specifically package two copies of their genomes during, virus assembly, a requirement for strand-transfer-mediated recombination, during reverse transcription. Genomic RNA exists in virions as dimers, and, the overlap of RNA elements that promote dimerization and encapsidation, suggests that these processes may be coupled. Both processes are mediated, by the nucleocapsid domain (NC) of the retroviral Gag polyprotein. Here we, show that dimerization-induced register shifts in base pairing within the, Psi-RNA packaging signal of Moloney murine leukaemia virus (MoMuLV) expose, conserved UCUG elements that bind NC with high affinity (dissociation, constant = 75 +/- 12 nM). These elements are base-paired and do not bind, NC in the monomeric RNA. The structure of the NC complex with a, 101-nucleotide 'core encapsidation' segment of the MoMuLV Psi site reveals, a network of interactions that promote sequence- and structure-specific, binding by NC's single CCHC zinc knuckle. Our findings support a, structural RNA switch mechanism for genome encapsidation, in which protein, binding sites are sequestered by base pairing in the monomeric RNA and, become exposed upon dimerization to promote packaging of a diploid genome.

About this Structure

1U6P is a Single protein structure of sequence from Moloney murine leukemia virus with ZN as ligand. Full crystallographic information is available from OCA.

Reference

Structural basis for packaging the dimeric genome of Moloney murine leukaemia virus., D'Souza V, Summers MF, Nature. 2004 Sep 30;431(7008):586-90. PMID:15457265

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