The Race against Protease Activation Defines the Role of ESCRTs in HIV Budding.
HIV virions assemble on the plasma membrane and bud out of infected cells using interactions with endosomal sorting complexes required for transport (ESCRTs). HIV protease activation is essential for maturation and infectivity of progeny virions, however, the precise timing of protease activation and its relationship to budding has not been well defined. We show that compromised interactions with ESCRTs result in delayed budding of virions from host cells. Specifically, we show that Gag mutants with compromised interactions with ALIX and Tsg101, two early ESCRT factors, have an average budding delay of ~75 minutes and ~10 hours, respectively. Virions with inactive proteases incorporated the full Gag-Pol and had ~60 minutes delay in budding. We demonstrate that during budding delay, activated proteases release critical HIV enzymes back to host cytosol leading to production of non-infectious progeny virions. To explain the molecular mechanism of the observed budding delay, we modulated the Pol size artificially and show that virion release delays are size-dependent and also show size-dependency in requirements for Tsg101 and ALIX. We highlight the sensitivity of HIV to budding "on-time" and suggest that budding delay is a potent mechanism for inhibition of infectious retroviral release.
Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, United States of America.
Mourad
M
Bendjennat
Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, United States of America.|Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah, United States of America.|Department of Biology, University of Utah, Salt Lake City, Utah, United States of America.
Saveez
S
Saffarian
D002460:Cell Line; D056827:Endosomal Sorting Complexes Required for Transport / Q000502:physiology*; D015658:HIV Infections / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D009010:Monte Carlo Method; D010447:Peptide Hydrolases / Q000378:metabolism; D057074:Virus Release / Q000502:physiology*; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000378:metabolism
D056827:Endosomal Sorting Complexes Required for Transport; D054301:gag Gene Products, Human Immunodeficiency Virus; D010447:Peptide Hydrolases