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A lysine ring in HIV capsid pores coordinates IP6 to drive mature capsid assembly

DOI: 10.1371/journal.ppat.1009164 DOI Help

Authors: Nadine Renner (MRC Laboratory of Molecular Biology) , Donna L. Mallery (MRC Laboratory of Molecular Biology) , K. M. Rifat Faysal (UNSW Sydney) , Wang Peng (UNSW Sydney) , David Jacques (UNSW Sydney) , Till Böcking (UNSW Sydney) , Leo C. James (MRC Laboratory of Molecular Biology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Plos Pathogens , VOL 17

State: Published (Approved)
Published: February 2021
Diamond Proposal Number(s): 15916 , 21426

Open Access Open Access

Abstract: The HIV capsid self-assembles a protective conical shell that simultaneously prevents host sensing whilst permitting the import of nucleotides to drive DNA synthesis. This is accomplished through the construction of dynamic, highly charged pores at the centre of each capsid multimer. The clustering of charges required for dNTP import is strongly destabilising and it is proposed that HIV uses the metabolite IP6 to coordinate the pore during assembly. Here we have investigated the role of inositol phosphates in coordinating a ring of positively charged lysine residues (K25) that forms at the base of the capsid pore. We show that whilst IP5, which can functionally replace IP6, engages an arginine ring (R18) at the top of the pore, the lysine ring simultaneously binds a second IP5 molecule. Dose dependent removal of K25 from the pore severely inhibits HIV infection and concomitantly prevents DNA synthesis. Cryo-tomography reveals that K25A virions have a severe assembly defect that inhibits the formation of mature capsid cones. Monitoring both the kinetics and morphology of capsids assembled in vitro reveals that while mutation K25A can still form tubes, the ability of IP6 to drive assembly of capsid cones has been lost. Finally, in single molecule TIRF microscopy experiments, capsid lattices in permeabilised K25 mutant virions are rapidly lost and cannot be stabilised by IP6. These results suggest that the coordination of IP6 by a second charged ring in mature hexamers drives the assembly of conical capsids capable of reverse transcription and infection.

Journal Keywords: Capsids; Virions; HIV; Reverse transcription; DNA synthesis; Nucleotides; Viral core; Phosphates

Diamond Keywords: Human Immunodeficiency Virus (HIV); Viruses

Subject Areas: Biology and Bio-materials

Instruments: I24-Microfocus Macromolecular Crystallography


Discipline Tags:

Life Sciences & Biotech Health & Wellbeing Infectious Diseases Pathogens Structural biology Chemistry Biochemistry

Technical Tags:

Diffraction Macromolecular Crystallography (MX)