title: The thermodynamics of Pr55Gag-RNA interaction regulate the assembly of HIV.
abstract: The interactions that occur during HIV Pr55Gag oligomerization and genomic RNA packaging are essential elements that facilitate HIV assembly. However, mechanistic details of these interactions are not clearly defined. Here, we overcome previous limitations in producing large quantities of full-length recombinant Pr55Gag that is required for isothermal titration calorimetry (ITC) studies, and we have revealed the thermodynamic properties of HIV assembly for the first time. Thermodynamic analysis showed that the binding between RNA and HIV Pr55Gag is an energetically favourable reaction (ΔG<0) that is further enhanced by the oligomerization of Pr55Gag. The change in enthalpy (ΔH) widens sequentially from: (1) Pr55Gag-Psi RNA binding during HIV genome selection; to (2) Pr55Gag-Guanosine Uridine (GU)-containing RNA binding in cytoplasm/plasma membrane; and then to (3) Pr55Gag-Adenosine(A)-containing RNA binding in immature HIV. These data imply the stepwise increments of heat being released during HIV biogenesis may help to facilitate the process of viral assembly. By mimicking the interactions between A-containing RNA and oligomeric Pr55Gag in immature HIV, it was noted that a p6 domain truncated Pr50Gag Δp6 is less efficient than full-length Pr55Gag in this thermodynamic process. These data suggest a potential unknown role of p6 in Pr55Gag-Pr55Gag oligomerization and/or Pr55Gag-RNA interaction during HIV assembly. Our data provide direct evidence on how nucleic acid sequences and the oligomeric state of Pr55Gag regulate HIV assembly.
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.|CSIRO Manufacturing, Parkville, Victoria, Australia.
authors.forename: Hanumant S
authors.initials: HS
authors.lastname: Tanwar
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.|CSIRO Manufacturing, Parkville, Victoria, Australia.
authors.forename: Keith K
authors.initials: KK
authors.lastname: Khoo
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.|CSIRO Australian Animal Health Laboratory, Geelong, Australia.
authors.forename: Megan
authors.identifier: 0000-0001-7988-7334
authors.initials: M
authors.lastname: Garvey
authors.affiliation: CSIRO Manufacturing, Parkville, Victoria, Australia.
authors.forename: Lynne
authors.initials: L
authors.lastname: Waddington
authors.affiliation: CSIRO Australian Animal Health Laboratory, Geelong, Australia.
authors.forename: Andrew
authors.identifier: 0000-0003-4905-9401
authors.initials: A
authors.lastname: Leis
authors.affiliation: GE Health, Life Science, Burnley, Australia.
authors.forename: Marcel
authors.initials: M
authors.lastname: Hijnen
authors.affiliation: Monash Institute of Pharmaceutical Science, Parkville, Victoria, Australia.
authors.forename: Tony
authors.initials: T
authors.lastname: Velkov
authors.affiliation: CSIRO Manufacturing, Clayton, Victoria, Australia.
authors.forename: Geoff J
authors.identifier: 0000-0002-5080-8791
authors.initials: GJ
authors.lastname: Dumsday
authors.affiliation: CSIRO Manufacturing, Parkville, Victoria, Australia.
authors.forename: William J
authors.initials: WJ
authors.lastname: McKinstry
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.|CSIRO Australian Animal Health Laboratory, Geelong, Australia.
authors.forename: Johnson
authors.identifier: 0000-0002-5229-5707
authors.initials: J
authors.lastname: Mak
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002151:Calorimetry; D002845:Chromatography; D015497:HIV-1 / Q000502:physiology*; D047468:Immunoprecipitation; D008854:Microscopy, Electron; D011498:Protein Precursors / Q000737:chemistry*; D012367:RNA, Viral / Q000737:chemistry*; D013816:Thermodynamics; D019065:Virus Assembly / Q000502:physiology*
chemical_list: D011498:Protein Precursors; D012367:RNA, Viral; C059767:p55 gag precursor protein, Human immunodeficiency virus 1