Structure of rRNA in the ribosome

Author(s):  
M. Boublik ◽  
J. S. Wall

Ribosomes are complex subcellular organelles playing a central role in protein biosynthesis. They are composed of more than fifty different proteins and three or four ribonucleic acids (rRNA) unevenly distributed (with no symmetry) between the large and small ribosomal subunit. It has been well established that ribosomal proteins and rRNAs are both involved in formation of the internal architecture of the ribosome as well as its function in protein synthesis. Understanding the fundamental relationship between structure and function requires establishment of the 3-D structure of the ribosome and its components at a molecular level.

Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.


Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.


Author(s):  
Anders Liljas ◽  
Suparna Sanyal

Abstract The large ribosomal subunit has a distinct feature, the stalk, extending outside the ribosome. In bacteria it is called the L12 stalk. The base of the stalk is protein uL10 to which two or three dimers of proteins bL12 bind. In archea and eukarya P1 and P2 proteins constitute the stalk. All these extending proteins, that have a high degree of flexibility due to a hinge between their N- and C-terminal parts, are essential for proper functionalization of some of the translation factors. The role of the stalk proteins has remained enigmatic for decades but is gradually approaching an understanding. In this review we summarise the knowhow about the structure and function of the ribosomal stalk till date starting from the early phase of ribosome research.


2020 ◽  
pp. 57-57
Author(s):  
Bogdan Jovanovic ◽  
Lisa Schubert ◽  
Fabian Poetz ◽  
Georg Stoecklin

Ribosomes, the catalytic machinery required for protein synthesis, are comprised of 4 ribosomal RNAs and about 80 ribosomal proteins in mammals. Ribosomes further interact with numerous associated factors that regulate their biogenesis and function. As mutations of ribosomal proteins and ribosome associated proteins cause many diseases, it is important to develop tools by which ribosomes can be purified efficiently and with high specificity. Here, we designed a method to purify ribosomes from human cell lines by C-terminally tagging human RPS9, a protein of the small ribosomal subunit. The tag consists of a flag peptide and a streptavidin-binding peptide (SBP) separated by the tobacco etch virus (TEV) protease cleavage site. We demonstrate that RPS9-Flag-TEV-SBP (FTS) is efficiently incorporated into the ribosome without interfering with regular protein synthesis. Using HeLa-GFP-G3BP1 cells stably expressing RPS9-FTS or, as a negative control, mCherry-FTS, we show that complete ribosomes as well as numerous ribosome-associated proteins are efficiently and specifically purified following pull-down of RPS9-FTS using streptavidin beads. This tool will be helpful for the characterization of human ribosome heterogeneity, post-translational modifications of ribosomal proteins, and changes in ribosome-associated factors after exposing human cells to different stimuli and conditions.


2018 ◽  
Author(s):  
Wenfa Ng

Ribosomes are the protein synthesis factories of a cell and thus are evolutionary conserved in structure and function. Comprising a large and small subunit, the ribosome is further made up of ribosomal proteins that give structure and function to different parts of the macromolecular complex. Current methods for isolating the ribosome include density gradient ultracentrifugation that separates the ribosome into the large and small subunit. Separation of the various ribosomal proteins that comprise each of the subunit would require a solubilization step followed by the use of sodium dodecyl sulphate and polyacrylamide gel electrophoresis (SDS-PAGE). However, possibility exists for the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to profile the set of ribosomal proteins that could be solubilized from each ribosome subunit. Using ribosomal protein amino acid sequence information from Kyoto Encyclopaedia of Genes and Genomes (KEGG), the molecular weight of each ribosomal protein from Pseudomonas aeruginosa PAO1 was calculated in this report. Obtained results revealed that each ribosomal protein had a unique mass that could be detected by mid-range MALDI-TOF MS instruments. More importantly, the mass of ribosomal proteins constitutes a unique mass fingerprint of each ribosome subunit, which accounts for the different structure and functions of the large and small ribosome subunit. Overall, current mass resolution of MALDI-TOF MS instruments could resolve ribosomal proteins and thus provides a tool for profiling the set of ribosomal proteins that constitute the large and small subunit of the ribosome.


1993 ◽  
Vol 26 (4) ◽  
pp. 365-421 ◽  
Author(s):  
M. S. P. Sansom

Transport of ions through channels is fundamental to a number of physiological processes, especially the electrical properties of excitable cells (Hille, 1992). To understand this process at a molecular level requires atomic resolution structures of channel proteins.


present-day discussions on chromosomal structure and function the old term chromomere’ (Fol 1891) is seldom mentioned and it may be debated whether at is still desirable to use such a term. Conventionally it describes the bead-like concentrations of chromatin linearly arranged along the chromosomal thread, without implications as to the structural basis of such a discontinuity. Two alternative interpretations of the chromomeric organization of the chromosome have been suggested, one in which the chromomeres were regarded as definite chromosomal bodies, different from the interchromomeric regions of the chromosome, and one which considered the chromomeres as structures resulting only from the local coiling of a continuous chromosomal thread. Neither the chromomere hypothesis (Belling 1928; Bridges 1935; Pontecorvo 1944) nor the chromonema hypothesis (Ris 1945) has been finally and universally accepted. This is because the morphological and cytogenetical evidence previously available was insufficient to extend our knowledge of chromosomal structure down to the molecular level. New approaches in this direction have recently been made by the combined use of cytological, autoradiographic and photometric methods. They draw new attention to the chromomere.


Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1035 ◽  
Author(s):  
Sophie Sleiman ◽  
Francois Dragon

Ribosome biogenesis is one of the most energy demanding processes in the cell. In eukaryotes, the main steps of this process occur in the nucleolus and include pre-ribosomal RNA (pre-rRNA) processing, post-transcriptional modifications, and assembly of many non-ribosomal factors and ribosomal proteins in order to form mature and functional ribosomes. In yeast and humans, the nucleolar RNA acetyltransferase Kre33/NAT10 participates in different maturation events, such as acetylation and processing of 18S rRNA, and assembly of the 40S ribosomal subunit. Here, we review the structural and functional features of Kre33/NAT10 RNA acetyltransferase, and we underscore the importance of this enzyme in ribosome biogenesis, as well as in acetylation of non-ribosomal targets. We also report on the role of human NAT10 in Hutchinson–Gilford progeria syndrome.


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