Role of metal ion-mediated interactions in the assembly and stability of Sesbania mosaic virus T=3 and T=1 capsids.
J Mol Biol
; 342(3): 1001-14, 2004 Sep 17.
Article
en En
| MEDLINE
| ID: mdl-15342252
Sesbania mosaic virus (SeMV) capsids are stabilized by RNA-protein, protein-protein and calcium-mediated protein-protein interactions. The removal of calcium has been proposed to be a prerequisite for the disassembly of the virus. The crystal structure of native T=3 SeMV capsid revealed that residues D146 and D149 from one subunit and Y205, N267 and N268 of the neighboring subunit form the calcium-binding site (CBS). The CBS environment is found to be identical even in the recombinant CP-NDelta65 T=1 capsids. Here, we have addressed the role of calcium and the residues involved in calcium co-ordination in the assembly and stability of T=3 and T=1 capsids by mutational analysis. Deletion of N267 and N268 did not affect T=3 or T=1 assembly, although the capsids were devoid of calcium, suggesting that assembly does not require calcium ions. However, the stability of the capsids was reduced drastically. Site-directed mutagenesis revealed that either a single mutation (D149N) or a double mutation (D146N-D149N) of SeMV coat protein affected drastically both the assembly and stability of T=3 capsids. On the other hand, the D146N-D149N mutation in CP-NDelta65 did not affect the assembly of T=1 capsid, although their stability was reduced considerably. Since the major difference between the T=3 and T=1 capsids is the absence of the N-terminal arginine-rich motif (N-ARM) and the beta-annulus from the subunits forming the T=1 capsids, it is possible that D149 initiates the N-ARM-RNA interactions that lead to the formation of the beta-annulus, which is essential for T=3 capsid assembly.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de la Cápside
/
Virus del Mosaico
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Mol Biol
Año:
2004
Tipo del documento:
Article
País de afiliación:
India
Pais de publicación:
Países Bajos