Residues in the HIV-1 capsid assembly inhibitor binding site are essential for maintaining the assembly-competent quaternary structure of the capsid protein.
Morphogenesis of infectious HIV-1 involves budding of immature virions followed by proteolytic disassembly of the Gag protein shell and subsequent assembly of processed capsid proteins (CA) into the mature HIV-1 core. The dimeric interface between C-terminal domains of CA (C-CA) has been shown to be important for both immature and mature assemblies. We previously reported a CA-binding peptide (CAI) that blocks both assembly steps in vitro. The three-dimensional structure of the C-CA/CAI complex revealed an allosteric effect of CAI that alters the C-CA dimer interface. Based on this structure, we now investigated the phenotypes of mutations in the binding pocket. CA variants carrying mutations Y169A, L211A, or L211S had a reduced affinity for CAI and were unable to form mature-like particles in vitro. These mutations also blocked morphological conversion to mature virions in tissue culture and abolished infectivity. X-ray crystallographic analyses of the variant C-CA domains revealed that these alterations induced the same allosteric change at the dimer interface observed in the C-CA/CAI complex. These results point to a role of key interactions between conserved amino acids in the CAI binding pocket of C-CA in maintaining the correct conformation necessary for mature core assembly.
Bartonova
Vanda
V
Department of Virology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Igonet
Sébastien
S
Sticht
Jana
J
Glass
Bärbel
B
Habermann
Anja
A
Vaney
Marie-Christine
MC
Sehr
Peter
P
Lewis
Joe
J
Rey
Felix A
FA
Kraüsslich
Hans-Georg
HG
D000595:Amino Acid Sequence; D001665:Binding Sites; D002213:Capsid / Q000187:drug effects* / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D015497:HIV-1 / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000494:pharmacology; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D019065:Virus Assembly / Q000187:drug effects*
D036022:Capsid Proteins; D010455:Peptides