Naslov
Isoleucyl-tRNA synthetase editing domain accepts broad range of amino acids that are efficiently discriminated at the synthetic active site
(Isoleucyl-tRNA synthetase editing domain accepts broad range of amino acids that are efficiently discriminated at the synthetic active site)

Autori
Živković, Igor ; Gruić Sovulj, Ita

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Programme and abstract book of the 20th FEBS Young Scientists’ Forum / - , 2021, 60-60

Skup
The 20th FEBS Young Scientists’ Forum 2021

Mjesto i datum
Lovran, Hrvatska, 15.06.2021. - 18.06.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
Isoleucyl-tRNA synthetase, non-cognate amino acids, post-transfer editing, substrate specificity

Sažetak
Aminoacyl-tRNA synthetases (aaRSs) activate amino acids and transfer them to cognate tRNAs. Some aaRSs cannot establish a required specificity in amino acid recognition and thus may erroneously activate noncognate amino acids with a frequency higher than 103. These enzymes evolved a separate editing domain to hydrolyze formed misaminoacylated tRNAs (post-transfer editing). An initial model of discrimination at the editing domain proposed that binding of the cognate amino acid is prevented by a steric clash. Yet, we showed that the cognate amino acid may bind at the editing site, but unproductively (previously published in Dulic et al. J Mol Biol (2018) 430, 1–16). To understand better what shaped selectivity of the editing domain we have used isoleucyl-tRNA synthetase (IleRS) as a model enzyme in our recent (previously published in Bilus et al. J Mol Biol (2019) 431, 1284–1297 ; Zivkovic et al. FEBS J (2020) 287, 800–813, doi: 10.1111/febs.15053) and novel work. We tested a broad range of substrates belonging to i) proteinogenic (Ile, Ala, Val, Leu, Thr, Ser and Met), ii) nonproteinogenic (a-aminobutyrate, norvaline (Nva) and norleucine), and iii) synthetic (di- and tri-c-fluoro-aaminobutyrate) amino acids. Among them, only Val and Nva mimic well the cognate Ile and were poorly discriminated (< 200-fold), while the others were well discriminated at the IleRS synthetic site (500- to 106-fold). Nevertheless, we prepared misacylated tRNAs with all tested amino acids and followed their hydrolysis in an independent assay. Surprisingly, all misacylated tRNAs were hydrolyzed by IleRS at similar rates (35–70 s- 1).Thus, how efficient amino acids were discriminated at the synthetic site and consequently whether these amino acids posed an evolutionary threat to translation fidelity does not determine the efficiency of their post- transfer editing. Only the cognate IletRNAIle was hydrolyzed slowly (0.058 s-1), suggesting that this is the main requirement that shaped specificity of the editing domain.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija

POVEZANOST RADA