Virus Structure & Assembly
3/8/2011 1:45:00 PM
CHARACTERIZATION OF THE INTERACTION OF THE DENGUE VIRUS CAPSID PROTEIN WITH LIPID DROPLETS
Ivo C. Martins
, Fabiana A. Carneiro
, Ronaldo Mohana-Borges
, André Faustino
, Renata M. Pereira
, Filomena A. Carvalho
, Miguel A. Castanho
, Fábio Almeida
, Nuno C. Santos
, Andrea T. Da Poian
Instituto de Medicina Molecular (IMM), Faculdade de Medicina da Universidade de Lisboa (FMUL), Lisbon, Portugal,
Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
Dengue virus affects 100 million people yearly, but this number may grow since
spp. mosquitoes, the disease vectors, are spreading to temperate climates, including in the USA. No effective vaccines are available. A poor understanding of the viral life cycle is to blame, especially regarding the viral assembly and encapsidation process, mediated by Dengue Virus Capsid Protein (DVCP). DVCP is a symmetric homodimmer
-helical protein that must interact with intracellular lipid droplets during viral encapsidation. DVCP charge distribution suggests that its
nonpolar region may interact with lipids and the
positive charged region could interact with viral RNA. By employing biophysical techniques combined with bioinformatics tools, we found this hypothesis correct.
Nuclear magnetic resonance (NMR) shows a strong interaction with lipid droplets on the N-terminus and the
region of DVCP and points to a conformational change transmitted to the
region (C-terminus) via specific residues located in the
region. Aligning DVCP sequence with 16
spp. capsid proteins demonstrates that the residues identified by NMR as important for the lipid droplets interaction are conserved in the genus. Moreover, Dengue and West-Nile virus capsid protein structures super-impose in the
helices, pointing to a fold conservation among
-helices superimpose with oligonucleotide binding motifs, being therefore likely to bind RNA. Upon interaction with DVCP, the zeta potential of lipid droplets progressively shifts from negative to positive values, suggesting the positive
4-helices exposure on the surface of the lipid droplet-DVCP conjugate.
Concluding, DVCP specifically interacts with lipid droplets via its N-terminus and the
region, resulting in conformational changes in the
region and, finally, the DVCP-RNA binding. These regions could thus be targeted in future dengue drug development strategies.
A.T. Da Poian:
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