Naslov
ALL BUT ONE: HOW NEGATIVE CATALYSIS SHAPED EVOLUTION OF THE ISOLEUCYL-TRNA SYNTHETASE'S EDITING DOMAIN

Autori
Živković, Igor ; Maršavelski, Aleksandra, Gruić- Sovulj, Ita

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

Izvornik
Solutions in Chemistry / Kassal, Petar ; Meštrović, Ernest ; Namjesnik, Danijel ; Ribić, Rosana ; Šekutor, Marina ; Tomišić, Vladislav ; Usenik, Andrea - Zagreb : Hrvatsko kemijsko društvo, 2022, 51-51

ISBN
978-953-8334-05-4

Skup
International Conference Solutions in Chemistry 2022

Mjesto i datum
Sveti Martin na Muri, Hrvatska, 08.11.2022. - 11.11.2002

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
Aminoacyl-tRNA synthetases, post-transfer editing, negative catalysis, amino acid specificity

Sažetak
Aminoacyl-tRNA synthetases (AARS) activate amino acids and transfer them to cognate tRNAs. Some AARS cannot achieve the required specificity in the initial amino acid recognition at the synthetic site. Those AARS can incorrectly activate non-cognate amino acids and transfer them to tRNA. To correct the mistake and ensure faithful protein biosynthesis, these AARSs evolved a separate editing domain aimed to hydrolyze erroneously aminoacylated tRNAs (post-transfer editing). To understand what shaped the selectivity of the editing site and how it is related to the initial amino acid selectivity at the synthetic site, we used Escherichia coli isoleucyl-tRNA synthetase (IleRS) as a model enzyme.1-3 We investigated the synthetic and editing reactions of IleRS using a wide range of amino acids, including non-proteinogenic and synthetic: Val, Nva, Leu, Thr, Met, Ser, Ala, Abu, Nle, F2Abu and F3Abu. Among these, only Val and Nva were poorly discriminated at the synthetic site (i.e. well activated and transferred to the tRNA) and thus can be considered as threat to the fidelity of translation. To our surprise, tRNAs misaminoacylated with all tested amino acids were rapidly hydrolyzed at the editing domain. Thus, it appears that amino acid’s physicochemical features and how well it is rejected at the synthetic site does not pose a significant difference. Only the hydrolysis of cognate Ile-tRNAIle (misediting) was slow, suggesting that the need to keep the cognate product out of editing strongly shaped the specificity of the editing domain. Detailed kinetic analysis revealed that IleRS employs Thr246 and His333 for specific destabilization of Ile-tRNAIle hydrolysis – strategy also known as negative catalysis. Such design enabled IleRS to have broad substrate acceptance at the editing site whilst maintaining a high specificity towards preventing the futile post-transfer editing cycles. This was the first time such broad substrate specificity, paired with negative catalysis, was observed for an AARS, and as such, it marks a new moment in the understanding these vital and ancient enzymes.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija

POVEZANOST RADA