A roadmap for rRNA folding and assembly during transcription.

Ribonucleoprotein (RNP) assembly typically begins during transcription when folding of the newly synthesized RNA is coupled with the recruitment of RNA-binding proteins (RBPs). Upon binding, the proteins induce structural rearrangements in the RNA that are crucial for the next steps of assembly. Focusing primarily on bacterial ribosome assembly, we discuss recent work showing that early RNA-protein interactions are more dynamic than previously supposed, and remain so, until sufficient proteins are recruited to each transcript to consolidate an entire domain of the RNP. We also review studies showing that stable assembly of an RNP competes against modification and processing of the RNA. Finally, we discuss how transcription sets the timeline for competing and cooperative RNA-RBP interactions that determine the fate of the nascent RNA. How this dance is coordinated is the focus of this review.