Molecular Chaperones and Quality Control in Noncoding RNA Biogenesis

Abstract

Although noncoding RNAs have critical roles in all cells, both the mechanisms by which these RNAs fold into functionalstructures and the quality control pathways that monitor correct folding are only beginning to be elucidated. Here, we discussseveral proteins that likely function as molecular chaperones for noncoding RNAs and review the existing knowledge on noncodingRNA quality control. One protein, the La protein, binds many nascent noncoding RNAs in eukaryotes and is requiredfor efficient folding of certain pre-tRNAs. In prokaryotes, the Sm-like protein Hfq is required for the function of many noncodingRNAs. Recent work in bacteria and yeast has revealed the existence of quality control systems involving polyadenylationof unstable noncoding RNAs followed by exonucleolytic degradation. In addition, the Ro protein, which is present inmany animal cells and also certain bacteria, binds misfolded noncoding RNAs and is proposed to function in RNA qualitycontrol.