Naslov
Interplay between synthetic and editing pathways in class I aminoacyl-tRNA synthetases

Autori
Nevena Cvetešić, Morana Dulić, John J. Perona, Ita Gruić-Sovulj

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

Izvornik
Abstracts book XXIV tRNA Conference / Michael Ibba, Omar Orellana - Lahti, 2012, 126-126

Skup
XXIV tRNA Conference

Mjesto i datum
Olmué, Čile, 02.12.2012. - 06.12.2012

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
leucyl-tRNA synthetase; isoleucyl-tRNA synthetase; hydrolytic editing; norvaline

Sažetak
Extensive steady-state and transient kinetics were used in analysis of synthetic and editing pathways in class I isoleucyl- valyl- and leucyl-tRNA synthetases from Escherichia coli (IleRS, ValRS, LeuRS, respectively). We find that kinetic partitioning of the aminoacyl-adenylate between transfer and hydrolysis in the synthetic site dictates the respective use of pre- versus post- transfer pathways [1]. In ValRS and LeuRS, rapid transfer of threonine and norvaline, respectively, ensures prevalence of the post-transfer pathway. In contrast, in IleRS, tRNA-dependent hydrolytic clearance of valyl-adenylate within the synthetic site competes well with a slow transfer step, making both pre- and post-transfer pathways necessary. We also found that kinetic partitioning between synthetic and editing pathways occurs at both pre- and post-transfer steps [2]. Fast hydrolysis of misacylated tRNAs within the CP1- editing site efficiently competes with their release from the enzyme, while slow deacylation of cognate Leu-tRNALeu ensures that product dissociation predominates. Further, the LeuRS editing site exhibits substantial specificity among aminoacyl-tRNA substrates, and the editing rate is limited by product release. Finally, fundamental differences between two of the primary gatekeepers of cellular fidelity were recognized. DNA-polymerases feature a highly specific synthetic site where cognate and non-cognate substrates are distinguished by binding and reaction kinetics, and its editing site is less specific. In contrast, editing aaRSs predominately use a highly specific editing site to eliminate non-cognate substrates. Dulic M, Cvetesic N, Perona JJ, Gruic-Sovulj I. (2010) J Biol Chem. 285, 23799-809. Cvetesic N, Perona JJ, Gruic-Sovulj I. (2012) J Biol Chem. 287, 25381-94.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija

POVEZANOST RADA