Matsuo et al., (2013). Coupled GTPase and remodelling ATPase activities form a checkpoint for ribosome export.
Protein biosynthesis is a very complicated, multistage process subjected to strict control. The genetic information has to be very carefully read and rewritten. The translation step involves ribosomes, RNA and many proteins, and its regulation begins in the nucleus. The detailed mechanism of such regulation is not yet fully understood. So far, most of the information comes from studies of prokaryotic organisms, however eukaryotes are more challenging. Yeasts can serve as a valuable model to study these mechanism in eukaryotes.
The authors of this article studied the regulation of the maturation of the large ribosomal subunit 60S in S. cerevisiae. They proved that the process is highly energy-consuming and one of the key proteins is the K+ dependent GTPase Nug2, which binds to the 60S pre-ribosome subunit and prevents association of Nmd3 proteins (binding of Nmd3 to the pre-ribosome leads to the change of conformation, which enables the release of pre-ribosome into cytoplasm). Therefore K+ dependent GTPase Nug2 prevents the premature release of the immature 60S subunit from the nucleus to cytoplasm.
The study showed competitive binding of both proteins to the 60S subunit of the pre-ribosome. The authors created a model of function of the maturation process of the large ribosomal subunit in Eukaryotes. The GTPase Nug2 protein in the presence of K+ ions and AAA-ATPase Rea1 is essential for proper functioning of this process
Relevance of the article:
Yeasts are an excellent model organism for studies aimed at understanding of many complex processes occurring in higher organisms. This study focused on the regulation process of ribosomes maturation in eukaryotes. This knowledge may be of importance for the development of research related to human health. GNL2 is the human ortholog of Nug2. It is highly expressed in proliferating cells and participates in the control of the cell cycle also in cancer cells.
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