While the active site of ribosomes is evolutionary extremely conserved, other parts of cytosolic ribosomes did change to adapt to an organism's need. One one hand these concerns ribosomal proteins, on the other hand expansion in the ribosomal RNA. The Polacek wrote a review on recent findings concerning their roles, mechanism of action and consequences of their absence focusing on one expansion segment in each subunit. Their review "adfs" was published in Biochemical Society Transactions.
Abstract
Ribosomes are universally conserved cellular machines that catalyze protein biosynthesis. The active sites underly immense evolutionary conservation resulting in virtually identical core structures of ribosomes in all domains of life including organellar ribosomes. However, more peripheral structures of cytosolic ribosomes changed during evolution accommodating new functions and regulatory options. The expansion occurred at the riboprotein level, including more and larger ribosomal proteins and at the RNA level increasing the length of ribosomal RNA. Expansions within the ribosomal RNA occur as clusters at conserved sites that face toward the periphery of the cytosolic ribosome. Recent biochemical and structural work has shed light on how rRNA-specific expansion segments (ESs) recruit factors during translation and how they modulate translation dynamics in the cytosol. Here we focus on recent work on yeast, human and trypanosomal cytosolic ribosomes that explores the role of two specific rRNA ESs within the small and large subunit respectively. While no single regulatory strategy exists, the absence of ESs has consequences for proteomic stability and cellular fitness, rendering them fascinating evolutionary tools for tailored protein biosynthesis.
Read the Publication in Biochemical Society Transactions (Open Access)
Abstract, figure and title from Rauscher and Polacek (2024) Biochem Soc Trans published under a CC BY 4.0 license.