Project description:Ribosome movement is not always smooth and is rather often impeded. For ribosome pauses, fundamental issues remain to be addressed, including where ribosomes pause on mRNAs, what kind of RNA/amino acid sequence causes this pause, and the physiological significance of this attenuation of protein synthesis. Here, we survey the positions of ribosome collisions caused by ribosome pauses in humans and zebrafish using modified ribosome profiling. Collided ribosomes, i.e., disomes, emerge at various sites: Pro-Pro/Gly/Asp motifs; Arg-X-Lys motifs; stop codons; and 3' untranslated regions. The electrostatic interaction between the charged nascent chain and the ribosome exit tunnel determines the eIF5A-mediated disome rescue at the Pro-Pro sites. In particular, XBP1u, a precursor of endoplasmic reticulum (ER)-stress-responsive transcription factor, shows striking queues of collided ribosomes and thus acts as a degradation substrate by ribosome-associated quality control. Our results provide insight into the causes and consequences of ribosome pause by dissecting collided ribosomes.
Project description:In protein synthesis, ribosome movement is not always smooth, rather often impeded by numerous reasons. Although the deceleration of ribosome defines the fates of the mRNAs and the synthesizing proteins, fundamental questions remain to be addressed including where ribosomes pause in mRNAs, what kind of RNA/amino acid context causes the pausing, and how physiologically significant the slowdown of protein synthesis is. Here we surveyed the position of ribosome collisions, caused by ribosome pausing, at a genome-wide level using the modified ribosome profiling in human and zebrafish. The collided ribosomes, i.e. disome, emerge at various sites; the proline-proline-lysine motif, stop codons, and 3′ UTR. The number of ribosomes in a collision is not limited to two, rather four to five, forming a queue of ribosomes. Especially, XBP1, a key modulator of unfolded protein response, shows striking queues of collided ribosomes thus acts as a substrate for ribosome-associated quality control (RQC) to avoid the accumulation of undesired proteins in the absence of stress. Our results provide an insight into the causes and the consequences of ribosome slowdowns by dissecting the specific architecture of ribosomes.
Project description:In protein synthesis, ribosome movement is not always smooth, rather often impeded by numerous reasons. Although the deceleration of ribosome defines the fates of the mRNAs and the synthesizing proteins, fundamental questions remain to be addressed including where ribosomes pause in mRNAs, what kind of RNA/amino acid context causes the pausing, and how physiologically significant the slowdown of protein synthesis is. Here we surveyed the position of ribosome collisions, caused by ribosome pausing, at a genome-wide level using the modified ribosome profiling in human and zebrafish. The collided ribosomes, i.e. disome, emerge at various sites; the proline-proline-lysine motif, stop codons, and 3′ UTR. The number of ribosomes in a collision is not limited to two, rather four to five, forming a queue of ribosomes. Especially, XBP1, a key modulator of unfolded protein response, shows striking queues of collided ribosomes thus acts as a substrate for ribosome-associated quality control (RQC) to avoid the accumulation of undesired proteins in the absence of stress. Our results provide an insight into the causes and the consequences of ribosome slowdowns by dissecting the specific architecture of ribosomes.
Project description:In protein synthesis, ribosome movement is not always smooth, rather often impeded by numerous reasons. Although the deceleration of ribosome defines the fates of the mRNAs and the synthesizing proteins, fundamental questions remain to be addressed including where ribosomes pause in mRNAs, what kind of RNA/amino acid context causes the pausing, and how physiologically significant the slowdown of protein synthesis is. Here we surveyed the position of ribosome collisions, caused by ribosome pausing, at a genome-wide level using the modified ribosome profiling in human and zebrafish. The collided ribosomes, i.e. disome, emerge at various sites; the proline-proline-lysine motif, stop codons, and 3′ UTR. The number of ribosomes in a collision is not limited to two, rather four to five, forming a queue of ribosomes. Especially, XBP1, a key modulator of unfolded protein response, shows striking queues of collided ribosomes thus acts as a substrate for ribosome-associated quality control (RQC) to avoid the accumulation of undesired proteins in the absence of stress. Our results provide an insight into the causes and the consequences of ribosome slowdowns by dissecting the specific architecture of ribosomes.