Cryo-electron microscopy of tubular arrays of HIV-1 Gag resolves structures essential for immature virus assembly.
The assembly of HIV-1 is mediated by oligomerization of the major structural polyprotein, Gag, into a hexameric protein lattice at the plasma membrane of the infected cell. This leads to budding and release of progeny immature virus particles. Subsequent proteolytic cleavage of Gag triggers rearrangement of the particles to form mature infectious virions. Obtaining a structural model of the assembled lattice of Gag within immature virus particles is necessary to understand the interactions that mediate assembly of HIV-1 particles in the infected cell, and to describe the substrate that is subsequently cleaved by the viral protease. An 8-Å resolution structure of an immature virus-like tubular array assembled from a Gag-derived protein of the related retrovirus Mason-Pfizer monkey virus (M-PMV) has previously been reported, and a model for the arrangement of the HIV-1 capsid (CA) domains has been generated based on homology to this structure. Here we have assembled tubular arrays of a HIV-1 Gag-derived protein with an immature-like arrangement of the C-terminal CA domains and have solved their structure by using hybrid cryo-EM and tomography analysis. The structure reveals the arrangement of the C-terminal domain of CA within an immature-like HIV-1 Gag lattice, and provides, to our knowledge, the first high-resolution view of the region immediately downstream of CA, which is essential for assembly, and is significantly different from the respective region in M-PMV. Our results reveal a hollow column of density for this region in HIV-1 that is compatible with the presence of a six-helix bundle at this position.
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany;Molecular Medicine Partnership Unit, European Molecular Biology Laboratory/Universitätsklinikum Heidelberg, Heidelberg, Germany;Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
Tanmay A M
TA
Bharat
Molecular Medicine Partnership Unit, European Molecular Biology Laboratory/Universitätsklinikum Heidelberg, Heidelberg, Germany;Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany;
Luis R
LR
Castillo Menendez
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany;
Wim J H
WJ
Hagen
Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany;
Vanda
V
Lux
Unité de Virologie Structurale, Departement Virologie, Institut Pasteur, 75724 Paris, France; andUnité Mixte de Recherche 3569, Centre National de la Recherche Scientifique, 75724 Paris, France.
Sebastien
S
Igonet
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany;
Martin
M
Schorb
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany;Molecular Medicine Partnership Unit, European Molecular Biology Laboratory/Universitätsklinikum Heidelberg, Heidelberg, Germany;
Florian K M
FK
Schur
Molecular Medicine Partnership Unit, European Molecular Biology Laboratory/Universitätsklinikum Heidelberg, Heidelberg, Germany;Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany; hans-georg.kraeusslich@med.uni-heidelberg.de john.briggs@embl.de.
Hans-Georg
HG
Kräusslich
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany;Molecular Medicine Partnership Unit, European Molecular Biology Laboratory/Universitätsklinikum Heidelberg, Heidelberg, Germany; hans-georg.kraeusslich@med.uni-heidelberg.de john.briggs@embl.de.
John A G
JA
Briggs
D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D015497:HIV-1 / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D043942:Nanotubes / Q000737:chemistry* / Q000821:virology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014771:Virion / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000378:metabolism
D036022:Capsid Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus
SP1; cryo-electron tomography; electron cryomicroscopy; helical reconstruction