engleski

Interaction of aminoacyl-tRNA synthetases with the archaeal ribosome

The aminoacyl-tRNA synthetases (aaRS) are essential enzymes catalyzing the formation of aminoacyl-tRNAs (aa-tRNAs), the immediate precursors for encoded peptides in ribosomal protein synthesis. Thus far, coupling of protein synthesis with upstream enzymatic reactions preparing aa-tRNA substrates for the translating ribosome has been less well understood. Former studies have suggested the link between tRNA aminoacylation and high-molecular-weight cellular material like cytoskelet, rRNA or ribosomes1, 2. Here we analyze the binding of selected aaRSs from archaeon Methanothermobacter thermautotrophicus to ribosomes. An atypical methanogenic type SerRS (mSerRS)3, 4, confined to certain archaea, forms a complex with M. thermautotrophicus ArgRS5, a synthetase that exists in mammalian cells either as a part of the multi-aaRS complex or as a free enzyme. Cosedimentation experiments and microscale thermophoresis (MST) analysis revealed that two synthetases reside in complex with 70S ribosomes. After separation of ribosomal subunits, aaRSs remained efficiently associated only with 50S particle. In accordance, the interaction with small ribosomal subunits was reduced to background in MST, indicating that the binding is mediated by the large ribosomal subunit. Main sites for synthetase binding were identified by crosslinking and surface plasmon resonance (SPR) and the model was generated using available structure data from M. thermautotrophicus ribosome6. Bioinformatics analysis of synonymous codons in M. thermautotrophicus supports the idea that deacylated tRNAs may be recharged by bound synthetases and reused in the vicinity of the ribosome for another cycle of elongation7-9.

aminoacyl-tRNA synthetase; ribosome

119-0982913-1358