RESUMO
The ribosome is a molecular machine that synthesizes polypeptides from aminoacyl-tRNAs according to the sequence of the mRNA template. Codon reading by the anticodon of tRNA is controlled by a network of ribosome contacts that are specific for each position of the codon-anticodon duplex and involve A-minor RNA interactions. Rapid and accurate tRNA selection is accomplished by switching the conformation of the decoding site between accepting and rejecting mode, regardless of the thermodynamic stability of the respective codon-anticodon complexes or their interactions at the decoding site. The forward reactions are particularly sensitive to mismatches and determine the variations in the extent of misreading of near-cognate codons, both during initial selection and proofreading. This review emphasizes the progress made in understanding the mechanisms that determine recognition and selection of tRNA by the translational machinery.
Assuntos
Anticódon/genética , Códon/genética , Ribossomos/metabolismo , Anticódon/metabolismo , Pareamento Incorreto de Bases/genética , Códon/metabolismo , GTP Fosfo-Hidrolases/metabolismo , Conformação de Ácido Nucleico , Biossíntese de Proteínas/genética , RNA de Transferência/química , RNA de Transferência/genética , RNA de Transferência/metabolismo , Ribossomos/química , Ribossomos/genéticaRESUMO
Protein synthesis in the cell is performed on ribosomes, large ribonucleoprotein particles, which in bacteria consist of three RNA molecules and over 50 proteins. This review summarizes recent progress in understanding the mechanisms of the elongation phase of protein synthesis. Results from rapid kinetic analysis of elongation reactions are discussed in the light of recent structural data.
