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bioRxiv · 10.1101/2025.08.27.672612

Cotranslational folding and maturation of HIV-1 protease

Westerfield, J. M.·Nicolaus, F.·Swanstrom, R. M.·von Heijne, G.
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Abstract

HIV-1 particle assembly depends critically on multiple proteolytic cleavages of viral polyproteins by the viral protease, PR. PR is translated as part of the Gag-Pro-Pol polyprotein, which undergoes autoproteolysis to liberate active, dimeric PR during virus particle maturation. Gag-Pro-Pol is produced via an infrequent -1 frameshifting event in ribosomes translating full length genomic RNA as Gag mRNA. Here, we study the cotranslational folding and autoproteolytic processing of frameshifted transframe-protease-reverse transcriptase (TF-PR-RT) constructs by in vitro translation. We demonstrate partial cotranslational folding of ribosome-bound PR at its conserved -helix near the C terminus. Unexpectedly, we find that the initial dimerization of TF-PR-RT involves ribosome-bound nascent chains that are then not further cleaved. Moreover, only ribosome-bound nascent chains are substrates for PR-catalyzed processing. These observations are consistent with a model for virion assembly in which dimerization of a subset of Pro-Pol precursors leads to cleavage of PR monomers that then carry out the bulk of the proteolytic processing needed for virion maturation and infectivity.

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Westerfield, J. M., Nicolaus, F., Swanstrom, R. M., von Heijne, G.. 2025-08-27. Cotranslational folding and maturation of HIV-1 protease. https://doi.org/10.1101/2025.08.27.672612

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