Protein and RNA chaperones.

Cells preserve macromolecular homeostasis by utilizing molecular chaperones that prevent aggregation or promote correct folding of protein and RNA. Here we discuss non-traditional proteinaceous chaperones like RNA-binding chaperones that work by modulating RNA structure, preventing aberrant interactions, and regulating intracellular granule dynamics. We also discuss the chaperone functions of other macromolecules such as nucleic acids, and in particular G-quadruplexes, which are very effective at preventing protein aggregation and accelerating protein folding. These chaperones are particularly important in G-quadruplex linked amyloid aggregation and repeat-expansion diseases such as Parkinson's disease and amyotrophic lateral sclerosis, where RNA aggregation and misfolded protein accumulation co-occur. By comparing protein and non-protein chaperone systems, we highlight the principles that underlie chaperone action across molecular classes.