RNA chaperone proteins play significant roles in diverse biological contexts. The most widely studied RNA chaperones are the retroviral nucleocapsid proteins (NC), also referred to as nucleic acid (NA) chaperones. Surprisingly, the biophysical properties of the NC proteins vary significantly for different viruses, and it appears that HIV-1 NC has optimal NA chaperone activity. In this review we discuss the physical nature of the NA chaperone activity of NC. We conclude that the optimal NA chaperone must saturate NA binding, leading to strong NA aggregation and slight destabilization of all NA duplexes. Finally, rapid kinetics of the chaperone protein interaction with NA is another primary component of its NA chaperone activity. We discuss these characteristics of HIV-1 NC and compare them with those of other NA binding proteins and ligands that exhibit only some characteristics of NA chaperone activity, as studied by single molecule DNA stretching.
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Ü -BOEFT#JPTDJFODF destabilize dsDNA and exhibit rapid kinetics simultaneously. of aggregation and ssDNA affinity is needed to optimize NA These characteristics must be carefully balanced for efficient chaperone activity during LINE-1 retrotransposition. chaperone activity, and they must also likely be tuned to the specific biological system in which they act. Multivalent cations Acknowledgements strongly interact with dsD%NA anPd inducOe obvPious aUggregEation.JTWe acUknSowleJdgCe fundVing frUom UFS National Institutes of Health However, instead of destabilizing dsDNA, the presence of mul-(R01GM072462) and the US National Science Foundation tivalent cations significantly stabilizes the dsDNA, increasing (MCB-0744456).
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- DNA condensation
- Force spectroscopy
- Nucleocapsid protein
- SSB protein