Arginyl-tRNA Synthetase Facilitates Complex Formation Between Seryl-tRNA Synthetase and its Cognate Transfer RNA

Several studies have revealed the involvement of multi aminoacyl-tRNA synthetase complexes (MSC) in archaeal and eukaryotic translation. Here we analyzed interactions of atypical Methanothermobacter thermautotrophicus seryl-tRNA synthetase (MtSerRS), transfer RNA (tRNA(Ser)) and arginyl-tRNA synthetase (ArgRS). Surface plasmon resonance (SPR) was used to determine dissociation constants for the MtSerRS:tRNA(Ser) complex and the results were consistent with cooperative binding of tRNA(Ser). This finding was supported by the ability of MtSerRS to bind two tRNAs in gel mobility shift assay. Notably, the MtSerRS:tRNA(Ser) complex formation was stimulated by MtArgRS, previously determined interacting partner of MtSerRS. MtArgRS decreases K-d for MtSerRS:tRNA(Ser) two-fold, but does not affect cooperative properties or stoichiometry of the complex. Further investigation of complex formation between MtSerRS and tRNA(Ser) showed that this molecular interaction is salt-dependent. The most pronounced improvements in binding were determined at high ionic strength, using Tris as a buffering agent, while the addition of Mg2+ ions led to the same SPR response. (doi: 10.5562/cca2146)