Affinity labelling in situ of the bL12 protein on E. coli 70S ribosomes by means of a tRNA dialdehyde derivative

C. Hountondji , J.B. Crechet , J.P. Le Caër , V. Lancelot , J.A.H. Cognet , S. Baouz

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J. Biochem., 1-12,1
Published 16 Aug. 2017
DOI: doi:10.1093/jb/mvx055

Abstract

In this report, we have used periodate-oxidized tRNA (tRNAox) as an affinity laleling reagent to demonstrate that: (i) the bL12 protein contacts the CCA-arm of P- site bound tRNA on the Escherichia coli 70S ribo- somes; (ii) the stoichiometry of labelling is one molecule of tRNAox bound to one polypeptide chain of endogen- ous bL12; (iii) cross-linking in situ of bL12 with tRNAox on the ribosomes provokes the loss of activity; (iv) intact tRNA protects bL12 in the 70S ribosomes against cross-linking with tRNAox; (v) both tRNAox and pyridoxal 50-phosphate (PLP) compete for the same or for proximal cross-linking site(s) on bL12 inside the ribosome; (vi) the stoichiometry of cross-link- ing of PLP to the recombinant E. coli bL12 protein is one molecule of PLP covalently bound per polypeptide chain; (vii) the amino acid residue of recombinant bL12 cross-linked with PLP is Lys-65; (viii) Lys-65 of E. coli bL12 corresponds to Lys-53 of eL42 which was previ- ously shown to cross-link with P-site bound tRNAox on human 80S ribosomes in situ; (ix) finally, E. coli bL12 and human eL42 proteins display significant primary structure similarities, which argues for evolutionary conservation of these two proteins located at the tRNA-CCA binding site on eubacterial and eukaryal ribosomes.

Cette publication est associée à :

Modélisation mésoscopique des biopolymères