ESCRT-III CHMP2A and CHMP3 form variable helical polymers in vitro and act synergistically during HIV-1 budding.
Cell Microbiol
; 15(2): 213-26, 2013 Feb.
Article
em En
| MEDLINE
| ID: mdl-23051622
ABSTRACT
The endosomal sorting complex required for transport-III (ESCRT-III) proteins are essential for budding of some enveloped viruses, for the formation of intraluminal vesicles at the endosome and for the abscission step of cytokinesis. ESCRT-III proteins form polymers that constrict membrane tubes, leading to fission. We have used electron cryomicroscopy to determine the molecular organization of pleiomorphic ESCRT-III CHMP2A-CHMP3 polymers. The three-dimensional reconstruction at 22 Å resolution reveals a helical organization of filaments of CHMP molecules organized in a head-to-tail fashion. Protease susceptibility experiments indicate that polymerization is achieved via conformational changes that increase the protomer stability. Combinatorial siRNA knockdown experiments indicate that CHMP3 contributes synergistically to HIV-1 budding, and the CHMP3 contribution is ~ 10-fold more pronounced in concert with CHMP2A than with CHMP2B. This is consistent with surface plasmon resonance affinity measurements that suggest sequential CHMP4B-CHMP3-CHMP2A recruitment while showing that both CHMP2A and CHMP2B interact with CHMP4B, in agreement with their redundant functions in HIV-1 budding. Our data thus indicate that the CHMP2A-CHMP3 polymer observed in vitro contributes to HIV-1 budding by assembling on CHMP4B polymers.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
HIV-1
/
Complexos Endossomais de Distribuição Requeridos para Transporte
/
Liberação de Vírus
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article