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EteRNA on FORA.tv – Open Education and the Future of Science Education

EteRNA on the web

 

Crystal structure of the eukaryotic ribosome. – F1000

F0035029-ribosomal_subunit_molecular_model-spl

from sciencephoto

This work describes for the first time the overall structure of the eukaryotic ribosome from yeast at 4.15 angstrom resolution, which reveals a considerably larger assembly and thus a greater degree of complexity than its prokaryotic counterpart. Despite significant differences between the structure of eukaryotic and prokaryotic ribosomes, the basic architecture remains similar.

Although structures have been reported for the large ribosomal subunit (50S) from Haloarcula marismortui {1} and the small ribosomal subunit (30S) from Thermus thermophilus {2}, the structure for the eukaryotic ribosome was unknown and, despite the conservation of both sequence and function among ribosomes, the eukaryotic ribosome was expected to contain significant differences in structure given the 40% increase in its size compared to its bacterial counterpart. The larger size of the eukaryotic ribosome results from the inclusion of rRNA expansion elements and ribosomal proteins unique to eukaryotes. The authors show that the rRNA expansion elements are located predominantly on the solvent-exposed sides at the periphery of both subunits and they suggest functions for several of these expansion elements and ribosomal proteins in translation initiation and elongation. Considerable differences in structure were observed for the entry and exit sites of the mRNA on the small subunit, suggesting roles that may be unique to eukaryotes, e.g. interactions with mRNA and initiation factors. In contrast to many of the observed differences, the intersubunit bridges observed in the crystal structure of the bacterial ribosome have corresponding bridges in the eukaryotic ribosome. Although this new structure of the complete 80S eukaryotic ribosome provides a basis for understanding the differences in structure between eukaryotic ribosomes and those in other kingdoms, it raises new questions about the roles of the rRNA expansion elements and the eukaryotic-specific ribosomal proteins that only additional high-resolution structures of the eukaryotic ribosomes in conjunction with tRNA, mRNA, initiation, elongation, and termination factors will be able to answer.

References:
{1} Ban et al. Science 2000, 289:905-20 [PMID:10937989].
{2} Jenner et al. Nat Struct Mol Biol 2010, 17:1072-8 [PMID:20694005].

Competing interests: None declared

Gallie D: “This work describes for the first time the overall structure of the eukaryotic ribosome from…” Evaluation of: [Ben-Shem A et al. Crystal structure of the eukaryotic ribosome. Science. 2010 Nov 26;
330(6008):12039; doi: 10.1126/science.1194294]. Faculty of 1000, 15 Feb 2011. F1000.com/6750956

Short form
Gallie D: 2011. F1000.com/6750956

 

Bringing RNA into View – RNA and Its Roles in Biology

via Learn Genetics

Chemists produce first high-resolution RNA ‘nano square’

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Abstract

The three-dimensional structures of noncoding RNA molecules reveal recurring architectural motifs that have been exploited for the design of artificial RNA nanomaterials. Programmed assembly of RNA nanoobjects from autonomously folding tetraloop–receptor complexes as well as junction motifs has been achieved previously through sequence-directed hybridization of complex sets of long oligonucleotides. Due to size and complexity, structural characterization of artificial RNA nanoobjects has been limited to low-resolution microscopy studies. Here we present the design, construction, and crystal structure determination at 2.2 Å of the smallest yet square-shaped nanoobject made entirely of double-stranded RNA. The RNA square is comprised of 100 residues and self-assembles from four copies each of two oligonucleotides of 10 and 15 bases length. Despite the high symmetry on the level of secondary structure, the three-dimensional architecture of the square is asymmetric, with all four corners adopting distinct folding patterns. We demonstrate the programmed self-assembly of RNA squares from complex mixtures of corner units and establish a concept to exploit the RNA square as a combinatorial nanoscale platform.

 

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Chemical Structure of RNA

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Crystal structure of the eukaryotic ribosome

Csh_cover2

CNRS: Le ribosome eucarypte dévoile enfin sa structure

Science: Crystal Structure of the Eukaryotic Ribosome

 

Scitable: Nucleic Acid Structure and Function, RNA, …

NUCLEIC ACID STRUCTURE AND FUNCTION

Lead Editor: Bob Moss

RNA, RNA functions, …

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