Review Lecture - Structure and evolution of ribosomes

Abstract

Ribosomes are the only cell organelles occurring in all organisms. E. coli ribosomes, which are the best characterized particles, consist of three RNAs and 53 proteins. All components have been isolated and characterized by chemical, physical and immunological methods. The primary structures of the RNAs and of all the proteins are known. Information about the secondary structure of the proteins derives from circular dichroism measurements and from secondary structure prediction methods. The tertiary structure is being studied by limited proteolysis, proton magnetic resonance and crystallization followed by X-ray analysis. Various methods are being used to elucidate the architecture of the ribosomal particle: three-dimensional image reconstruction of crystals of bacterial ribosomes and/or their subunits; immune electron microscopy; neutron scattering; protein-protein, protein-RNA and RNA‒RNA crosslinking; total reconstitution of ribosomal subunits. The results from these studies yield valuable information on the architecture of the ribosomal particle. Many mutants have been isolated in which one or a few ribosomal proteins are altered or even deleted. The genetic and biochemical characterization of these mutants allows conclusions about the importance of these proteins for the function of the ribosome. Ribosomal proteins from various prokaryotic and eukaryotic species have been compared by two-dimensional gel electrophoresis, immunological methods, reconstitution and amino acid sequence analysis. These studies show a strong homology among prokaryotic ribosomal proteins but only a weak homology between proteins from prokaryotic and eukaryotic ribosomes. Comparison of the primary and secondary struc­tures of the ribosomal RNAs from various organisms shows that the secondary structure of the RNA molecules has been strongly conserved throughout evolution.

The process of mammalian mitochondrial protein synthesis

“…The best characterised mt-mRNA-specific proteins involved in transcript stability are the LRPPRC/SLIRP complex (Sasarman et al 2010) and FASTKD4, which prevents their degradation (Wolf and Mootha 2014). The only protein-coding transcript derived from the light strand, MTND6 , interacts with the mitochondrial isoform of FASTK (Jourdain et al 2015) and GRSF1, which modulates its stability (Antonicka et al 2013; Jourdain et al 2013).…”

The Inoculation Method Could Impact the Outcome of Microbiological Experiments

“…When cells are inoculated into fresh culture medium, they initially enter the lag phase. During the lag phase, cells adjust to the fresh medium by synthesizing proteins that prepare the cells for growth (9)(10)(11)(12)(13)(14). This phase varies in length, depending on the growth state of the inoculated cells, and the entire population of the culture consists of the inoculum.…”