Abstract: In the cell, proteins are synthesized from amino acids by the ribosome using messenger RNA as the template. The ribosome is a large macromolecular assembly consisting of RNA and proteins. In bacteria, the translating 70S ribosome is formed from two unequally sized subunits: the large 50S and the small 30S subunit. Structures of both ribosomal subunits have been determined at near-atomic resolution. The large ribosomal subunits are from the halophilic archaebacterium Haloarcula marismortui1 and from the eubacterium Deinococcus radiodurans 2 . The small subunit has been solved from the thermophilic eubacterium Thermus thermophilus 3,4 . The structure of the 70S ribosome was determined from Thermus thermophilus with mRNA and tRNAs at a resolution of 5.5 A 5 . More recently, the 70S ribosome from Escherichia coli was published at a resolution of 9 A 6 . Furthermore, several ribosomal structures in complex with tRNA analogues 7-10 , small translation factors 11 and antibiotics 8,9,12-15 were solved giving further insight in the molecular mechanism of protein synthesis. The small subunit of the ribosome is responsible for binding mRNA and selection of the cognate aminoacyl-tRNA. Based on early electron microscopic studies, the 30S subunit is classically divided into head, body, neck, shoulder and platform (Fig.1). It consists of one 16S rRNA chain and 20 ribosomal proteins (S1-S20). The shape of the small subunit is mostly determined by ribosomal RNA. The proteins are distributed over the top, sides and back of the 30S subunit, while the interface with the 50S subunit is
Publication Year: 2005
Publication Date: 2005-12-30
Language: en
Type: book-chapter
Indexed In: ['crossref']
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