Probing Nucleation, Reverse Annealing, and Chaperone Function Along the Reaction Path of HIV-1 Single-strand Transfer
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Reverse transcription of the HIV-1 genome involves several nucleic acid rearrangement steps that are catalyzed (chaperoned) by the nucleocapsid protein (NC), including the annealing of the transactivation response region (TAR) RNA of the genome to the complementary sequence (TAR DNA) in minus-strand strong-stop DNA. It has been extremely challenging to obtain unambiguous mechanistic details on the annealing process at the molecular level because of the kinetic involvement of a complex and heterogeneous set of nucleic acid/protein complexes of variable structure and variable composition. Here, we investigate the in vitro annealing mechanism using a multistep single-molecule spectroscopy kinetic method. In this approach, an immobilized hairpin is exposed to a multistep programmed concentration sequence of NC, model complementary targeted-oligonucleotides, and buffer-only solutions. The sequence controllably "drags" single immobilized TAR hairpins among the kinetic stable states of the reaction mechanism; i.e., reactants, intermediates, and products. This single-molecule spectroscopy method directly probes kinetic reversibility and the chaperone (catalytic) role of NC at various stages along the reaction sequence, giving access to previously inaccessible kinetic processes and rate constants. By employing target oligonucleotides for specific TAR regions, we kinetically trap and investigate structural models for putative nucleation complexes for the annealing process. The new results lead to a more complete and detailed understanding of the ability of NC to promote nucleic acid/nucleic acid rearrangement processes. This includes information on the ability of NC to chaperone "reverse annealing" in single-strand transfer and the first observation of partially annealed, conformational substates in the annealing mechanism.
Kinetic Studies on the Interaction of HIV-1 Gag Protein with the HIV-1 RNA Packaging Signal.
Rink C, Kroupa T, Datta S, Rein A Viruses. 2024; 16(10).
PMID: 39459852 PMC: 11512386. DOI: 10.3390/v16101517.
Jiang K, Humbert N, K K S, Rouzina I, Mely Y, Westerlund F Nucleic Acids Res. 2021; 49(8):4550-4563.
PMID: 33872352 PMC: 8096146. DOI: 10.1093/nar/gkab236.
Single-molecule Förster resonance energy transfer studies of RNA structure, dynamics and function.
Helm M, Kobitski A, Nienhaus G Biophys Rev. 2017; 1(4):161.
PMID: 28510027 PMC: 5418384. DOI: 10.1007/s12551-009-0018-3.
Pulse dipolar ESR of doubly labeled mini TAR DNA and its annealing to mini TAR RNA.
Sun Y, Borbat P, Grigoryants V, Myers W, Freed J, Scholes C Biophys J. 2015; 108(4):893-902.
PMID: 25692594 PMC: 4336369. DOI: 10.1016/j.bpj.2014.12.028.
Sosic A, Cappellini M, Scalabrin M, Gatto B J Vis Exp. 2015; (95):52474.
PMID: 25650789 PMC: 4354545. DOI: 10.3791/52474.