Proteins that chaperone rna regulation

Figure 1. Iterative annealing of RNA by chaperones
Typical kinetic mechanism for forming RNA secondary structure (left) and tertiary structure 
(right). Assembly of the double helices (cylinders) into compact intermediates is followed 
by further reorganization of tertiary interactions to produce the native RNA. Because the 
RNA may adopt many secondary structures, some molecules fold directly to the native 
structure (top path) while others become trapped in non-native structures. In the classic 
iterative annealing model, chaperones (gold, bottom) bind and partially unfold misfolded 
intermediates, then release the unfolded RNA to fold again. Adapted from (60) with 
permission.
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Figure 2. Chaperone-assisted annealing of anti-sense RNA
Annealing of anti-sense or trans acting sRNAs with a complementary RNA target typically 
begins with base pairing between two hairpin loops (kissing complex) or a loop and a single 
strand (middle path). This is followed by extension of base pairing, which often requires 
refolding of adjacent sequences. HIV nucleocapsid (NCp7) and Rom/Rop promote 
annealing by disrupting secondary structure in each RNA, lowing the energetic barriers for 
extending the anti-sense interactions (top path). NCp7 can also aggregate RNA strands to 
speed up initiation of base pairing. Hfq facilitates sRNA-mRNA base pairing by forming a 
ternary complex with both RNAs that increases the rate of helix nucleation (bottom path). 
Hfq can also favor anti-sense base pairing by restructuring one or both RNAs.
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Document Outline

• Abstract
• INTRODUCTION
  • RNA folding and the need for RNA chaperones
  • Thermodynamic limits to passive unfolding of RNA
  • Transient interactions drive iterative chaperone cycles
  • RNA unfolding by capturing single-strands
  • Multi-domain interactions between chaperones and RNA
  • Ring-shaped chaperones for small RNAs
  • RNA chaperones drive sRNA competition and target selection
  • Intrinsically disordered domains in RNA chaperones
• CONCLUSION
• References
• Figure 1
• Figure 2