Elongation factor‐dependent reactions on ribosomes deprived of proteins L7 and L12

Koteliansky, Victor; Domogatsky, Sergei P.; Gudkov, A.T.; Spirin, Alexander S.

doi:10.1016/0014-5793(77)80003-3

Cited by 41 publications

(1 citation statement)

References 17 publications

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“…Ribosomes depleted of L7/12 are impaired in factor functions, and the activity is restored by the addition of L7/12 ( − ). It is generally accepted that L7/12 is important for EF-G-dependent GTP hydrolysis on the ribosome, because the removal of L7/12 resulted in a 85−98% inhibition of the reaction measured under multiple turnover conditions ( − ). The effect of L7/12 on EF-G binding to the ribosome is less clear, as reported reductions of binding varied between 15 and 90% ( 38 , 39 , 41 ).…”

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GTPase Activation of Elongation Factors Tu and G on the Ribosome

2002

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The GTPase activity of elongation factors Tu and G is stimulated by the ribosome. The factor binding site is located on the 50S ribosomal subunit and comprises proteins L7/12, L10, L11, the L11-binding region of 23S rRNA, and the sarcin-ricin loop of 23S rRNA. The role of these ribosomal elements in factor binding, GTPase activation, or functions in tRNA binding and translocation, and their relative contributions, is not known. By comparing ribosomes depleted of L7/12 and reconstituted ribosomes, we show that, for both factors, interactions with L7/12 and with other ribosomal residues contribute about equally and additively to GTPase activation, resulting in an overall 10(7)-fold stimulation. Removal of L7/12 has little effect on factor binding to the ribosome. Effects on other factor-dependent functions, i.e., A-site binding of aminoacyl-tRNA and translocation, are fully explained by the inhibition of GTP hydrolysis. Based on these results, we propose that L7/12 stimulates the GTPase activity of both factors by inducing the catalytically active conformation of the G domain. This effect appears to be augmented by interactions of other structural elements of the large ribosomal subunit with the switch regions of the factors.

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GTPase Activation of Elongation Factors Tu and G on the Ribosome

2002

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Structural comparison of the prokaryotic ribosomal proteins L7/L12 and L30

Leijonmarck¹,

Appelt²,

Badger³

et al. 1988

Proteins

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The structures of two prokaryotic ribosomal proteins, the carboxyterminal half of L7/L12 from Escherichia coli (L12CTF) and L30 from Bacilus stearothermophilus display a remarkably similar fold in which alpha-helices pack onto one side of an antiparallel, three-stranded, beta-pleated sheet. A detailed comparison of the structures by least-squares methods reveals that more than two-thirds of the alpha carbons can be superimposed with a root mean square distance of 2.33 A. The principal difference is an extra alpha-helix in L12CTF. The sequences of the proteins display a distinct conservation in regions which are crucial to the common fold, in particular the hydrophobic core. It is proposed that the similarity is a result of divergent evolution.

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