Assembly of multicomponent machines inRNAmetabolism: A common theme inmRNAdecay pathways

Abstract

Multicomponent protein-RNA complexes comprising a ribonuclease and partner RNA helicase facilitate the turnover of mRNA in all domains of life. While these higher-order complexes provide an effective means of physically and functionally coupling the processes of RNA remodeling and decay, most ribonucleases and RNA helicases do not exhibit sequence specificity in RNA binding. This raises the question as to how these assemblies select substrates for processing and how the activities are orchestrated at the precise moment to ensure efficient decay. The answers to these apparent puzzles lie in the auxiliary components of the assemblies that might relay decay-triggering signals.Given their function within the assemblies, these components may be viewed as "sensors." The functions and mechanisms of action of the sensor components in various degradation complexes in bacteria and eukaryotes are highlighted here to discuss their roles in RNA decay processes.

Modulation of RNA-binding properties of the RNA helicase UPF1 by its activator UPF2

“…These enzymes are molecular motors that harness the energy of ATP binding and hydrolysis to bring about conformational changes in RNA, which facilitate binding of some protein factors while preventing others from associating with the RNA. RNA helicases can also mediate protein–protein interactions, often acting as scaffolds for mRNP assembly ( Linder and Jankowsky 2011 ; Bourgeois et al 2016 ; Machado de Amorim and Chakrabarti 2021 ).…”