Degenerate RNA packaging signals in the genome of Satellite Tobacco Necrosis Virus: implications for the assembly of a T=1 capsid.
J Mol Biol
; 413(1): 51-65, 2011 Oct 14.
Article
en En
| MEDLINE
| ID: mdl-21839093
ABSTRACT
Using a recombinant, T=1 Satellite Tobacco Necrosis Virus (STNV)-like particle expressed in Escherichia coli, we have established conditions for in vitro disassembly and reassembly of the viral capsid. In vivo assembly is dependent on the presence of the coat protein (CP) N-terminal region, and in vitro assembly requires RNA. Using immobilised CP monomers under reassembly conditions with "free" CP subunits, we have prepared a range of partially assembled CP species for RNA aptamer selection. SELEX directed against the RNA-binding face of the STNV CP resulted in the isolation of several clones, one of which (B3) matches the STNV-1 genome in 16 out of 25 nucleotide positions, including across a statistically significant 10/10 stretch. This 10-base region folds into a stem-loop displaying the motif ACAA and has been shown to bind to STNV CP. Analysis of the other aptamer sequences reveals that the majority can be folded into stem-loops displaying versions of this motif. Using a sequence and secondary structure search motif to analyse the genomic sequence of STNV-1, we identified 30 stem-loops displaying the sequence motif AxxA. The implication is that there are many stem-loops in the genome carrying essential recognition features for binding STNV CP. Secondary structure predictions of the genomic RNA using Mfold showed that only 8 out of 30 of these stem-loops would be formed in the lowest-energy structure. These results are consistent with an assembly mechanism based on kinetically driven folding of the RNA.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
ARN Viral
/
Cápside
/
Ensamble de Virus
/
Virus Satélite de la Necrosis del Tabaco
/
Proteínas de la Cápside
/
Multimerización de Proteína
Tipo de estudio:
Prognostic_studies
Idioma:
En
Año:
2011
Tipo del documento:
Article