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The Mechanism for Activation of GTP Hydrolysis on the Ribosome

2010; American Association for the Advancement of Science; Volume: 330; Issue: 6005 Linguagem: Inglês

10.1126/science.1194460

1095-9203

Rebecca M. Voorhees, T.M. Schmeing, Ann C. Kelley, V. Ramakrishnan,

Enzyme Structure and Function

Protein synthesis requires several guanosine triphosphatase (GTPase) factors, including elongation factor Tu (EF-Tu), which delivers aminoacyl-transfer RNAs (tRNAs) to the ribosome. To understand how the ribosome triggers GTP hydrolysis in translational GTPases, we have determined the crystal structure of EF-Tu and aminoacyl-tRNA bound to the ribosome with a GTP analog, to 3.2 angstrom resolution. EF-Tu is in its active conformation, the switch I loop is ordered, and the catalytic histidine is coordinating the nucleophilic water in position for inline attack on the γ-phosphate of GTP. This activated conformation is due to a critical and conserved interaction of the histidine with A2662 of the sarcin-ricin loop of the 23S ribosomal RNA. The structure suggests a universal mechanism for GTPase activation and hydrolysis in translational GTPases on the ribosome.