RNA and Nucleocapsid Are Dispensable for Mature HIV-1 Capsid Assembly

Copyright © 2015, American Society for Microbiology. All Rights Reserved..

UNLABELLED: Human immunodeficiency virus type 1 (HIV-1) is released from infected cells in an immature, noninfectious form in which the structural polyprotein Gag is arranged in a hexameric lattice, forming an incomplete spherical shell. Maturation to the infectious form is mediated by the viral protease, which cleaves Gag at five sites, releasing the CA (capsid) protein, which forms a conical capsid encasing the condensed RNA genome. The pathway of this structural rearrangement is currently not understood, and it is unclear how cone assembly is initiated. RNA represents an integral structural component of retroviruses, and the viral nucleoprotein core has previously been proposed to nucleate mature capsid assembly. We addressed this hypothesis by replacing the RNA-binding NC (nucleocapsid) domain of HIV-1 Gag and the adjacent spacer peptide 2 (SP2) by a leucine zipper (LZ) protein-protein interaction domain [Gag(LZ)] in the viral context. We found that Gag(LZ)-carrying virus [HIV(LZ)] was efficiently released and viral polyproteins were proteolytically processed, though with reduced efficiency. Cryo-electron tomography revealed that the particles lacked a condensed nucleoprotein and contained an increased proportion of aberrant core morphologies caused either by the absence of RNA or by altered Gag processing. Nevertheless, a significant proportion of HIV(LZ) particles contained mature capsids with the wild-type morphology. These results clearly demonstrate that the nucleoprotein complex is dispensable as a nucleator for mature HIV-1 capsid assembly in the viral context.

IMPORTANCE: Formation of a closed conical capsid encasing the viral RNA genome is essential for HIV-1 infectivity. It is currently unclear what viral components initiate and regulate the formation of the capsid during virus morphogenesis, but it has been proposed that the ribonucleoprotein complex plays a role. To test this, we prepared virus-like particles lacking the viral nucleocapsid protein and RNA and analyzed their three-dimensional structure by cryo-electron tomography. While most virions displayed an abnormal morphology under these conditions, some particles showed a normal mature morphology with closed conical capsids. These data demonstrate that the presence of RNA and the nucleocapsid protein is not required for the formation of a mature, cone-shaped HIV-1 capsid.

Medienart:

E-Artikel

Erscheinungsjahr:

2015

Erschienen:

2015

Enthalten in:

Zur Gesamtaufnahme - volume:89

Enthalten in:

Journal of virology - 89(2015), 19 vom: 16. Okt., Seite 9739-47

Sprache:

Englisch

Beteiligte Personen:

Mattei, Simone [VerfasserIn]
Flemming, Annica [VerfasserIn]
Anders-Össwein, Maria [VerfasserIn]
Kräusslich, Hans-Georg [VerfasserIn]
Briggs, John A G [VerfasserIn]
Müller, Barbara [VerfasserIn]

Links:

Volltext

Themen:

Basic-Leucine Zipper Transcription Factors
GCN4 protein, S cerevisiae
HIV Core Protein p24
Journal Article
P24 protein, Human Immunodeficiency Virus Type 1
RNA, Viral
Research Support, Non-U.S. Gov't
Saccharomyces cerevisiae Proteins

Anmerkungen:

Date Completed 07.12.2015

Date Revised 13.11.2018

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1128/JVI.00750-15

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM25092434X