Biological consequences of error during ribosome biogenesis

Abstract

Rpl24, a eukaryotic 60S ribosomal protein, forms inter-subunit bridges. Lack of Rpl24 protein may weaken inter-subunit association, introducing problems during translation such as ribosome stalling. Ribosome stalling produces stalled polypeptides which accumulate to form toxic aggregates if undegraded. Past studies usually focused on aberrant messenger RNAs (mRNAs) resulting in ribosome stalling, however, few have focused on defective ribosomes as a potential cause. Here, I aimed to show that incomplete ribosomes that may arise due to errors during ribosome biogenesis can trigger translation arrest, using Saccharomyces cerevisiae (S. cerevisiae) as a model organism. To explore impact of Rpl24 deletion on translation, I observed nascent protein aggregation and toxicity of 4 different Rpl24 constructs: 3 truncated mutants, Rpl24 with N-terminal 1-65 amino acids (aa) (Rpl24 (65)), 1-80 aa (Rpl24 (80)) and 1-111aa (Rpl24 (111)), plus the full-length protein (Rpl24 (FL)). More truncations would increasingly disrupt the inter-subunit bridge. Rpl24 (65) grows slower compared to Rpl24 (80)/((111)/(FL). Hence, Rpl24 (80) is sufficient for normal Rpl24 function, indicating that the important domain of Rpl24 lies between the 65th and 80th aa. This study provides insight into the importance of ribosomal inter-subunit bridges and mechanisms underlying ribosomal stalling.