Related Experiment Video

Updated: Sep 29, 2026

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes
08:21

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes

Published on: July 28, 2016

The PPPY motif of human T-cell leukemia virus type 1 Gag protein is required early in the budding process

Isabelle Le Blanc1, Marie-Christine Prévost, Marie-Christine Dokhélar

  • 1INSERM U332, Institut Cochin de Génétique Moléculaire. Unité d'Oncologie Virale, Institut Pasteur, Paris, France.

Journal of Virology
|September 5, 2002
PubMed

Insights

The human T-cell leukemia virus type 1 (HTLV-1) PPPY motif is essential for virus production. Mutating this L domain halts virus budding earlier than other retroviruses, suggesting a continuous budding process.

Area of Science:

  • Virology
  • Molecular Biology
  • Cell Biology

Background:

  • Late-acting domains (L domains) in Gag proteins are crucial for retroviral budding.
  • The specific role of L domains in human T-cell leukemia virus type 1 (HTLV-1) budding remains incompletely understood.

Purpose of the Study:

  • To investigate the role of the candidate L domain motif PPPY in HTLV-1 virus production.
  • To determine the stage of the budding process affected by mutation of the HTLV-1 PPPY motif.

Main Methods:

  • Site-directed mutagenesis of the HTLV-1 Gag protein to alter the PPPY motif.
  • Analysis of viral particle production and budding intermediates using electron microscopy and biochemical assays.

Main Results:

  • Mutation of the PPPY motif significantly impaired HTLV-1 virus production.
  • HTLV-1 particles with mutated PPPY motifs accumulated at an earlier stage of budding compared to mutations in other known retroviral L domains.
  • This suggests the PPPY motif plays a distinct role in the late stages of viral egress.

Conclusions:

  • The PPPY motif is essential for efficient HTLV-1 release.
  • The findings indicate that retroviral budding may represent a dynamic continuum from initial bud formation to final membrane fission, with distinct L domains influencing different phases.

More Related Videos

Accessing Early Differentiation of Virus-Specific Follicular Helper CD4+ T Cell in Acute LCMV-Infected Mice05:03

Accessing Early Differentiation of Virus-Specific Follicular Helper CD4+ T Cell in Acute LCMV-Infected Mice

Published on: April 26, 2024

A Restriction Enzyme Based Cloning Method to Assess the In vitro Replication Capacity of HIV-1 Subtype C Gag-MJ4 Chimeric Viruses14:23

A Restriction Enzyme Based Cloning Method to Assess the In vitro Replication Capacity of HIV-1 Subtype C Gag-MJ4 Chimeric Viruses

Published on: August 31, 2014

Related Concept Videos

Inhibitors of Virion Maturation and Assembly01:19

Inhibitors of Virion Maturation and Assembly

As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Leaky Scanning02:28

Leaky Scanning

During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA.  Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
Rab Proteins01:14

Rab Proteins

Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Initiation of Translation02:33

Initiation of Translation

Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Retrovirus Life Cycles01:10

Retrovirus Life Cycles

Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the retrovirus to...