Naslov
Seryl-tRNA synthetase· tRNASer noncovalent interactions and their role in the fidelity of aminoacylation

Autori
Gruić-Sovulj, Ita ; Landeka, Irena ; Kamenski, Tomislav ; Weygand-Đurašević, Ivana

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

Izvornik
Sažetci = Abstracts ; Program XVII. Hrvatskog skupa kemičara i kemijskih inženjera / Vicković, Ivan - Zagreb : Hrvatsko društvo kemijskih inženjera i tehnologa (HDKI) ; Hrvatsko kemijsko drustvo, 2001

ISBN
953-6894-05-X

Skup
XVII. Hrvatski skup kemičara i kemijskih inženjera

Mjesto i datum
Osijek, Hrvatska, 10.06.2001. - 13.06.2001

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
aminoacyl-tRNA synthetases; tRNA; macromolecular complexes

Sažetak
Aminoacyl-tRNA synthetases (aaRS) catalyze formation of the ester bond between cognate pair of amino acid and tRNA. The reaction proceeds in a two steps ; first is the activation of amino acid in an ATP-dependent manner (stable enzyme bound aminoacyl-adenylate intermediate is formed) and second is the transfer of activated acyl group to 3’ -end of tRNA. Seryl-tRNA synthetase (SerRS) from yeast Saccharomyces cerevisiae recognizes serine, ATP and tRNASer and produces seryl-tRNASer. If functional tRNASer is not present in the reaction mixture, seryl-adenylate formation catalyzed by SerRS can be detected. It is known that noncovalent interactions between aaRS and tRNA are crucial for the accuracy of cognate tRNA selection. Noncovalent complex between SerRS and cognate tRNASer was detected by gel retardation assay. According to previously done MALDI-MS experiments [1] and SerRS/tRNASer molar ratio used for complex formation, it was concluded that in this experimental setup dimer of SerRS forms noncovalent complex with one molecule of tRNASer. It was observed [2] that SerRS displays higher affinity toward serine in the overall aminoacylation assay than in the amino acid activation reaction deprived of tRNA. Here we present direct kinetic proof that noncovalent interactions between SerRS and tRNASer induce local conformational change in the active site of SerRS leading to optimized serine binding site, but without influence on ATP binding site. The kinetic study was designed to measure KM value for serine and ATP in the activation reaction with and without tRNASer analogues unable to accept serine. The order of magnitude decrease of KM value for serine in the presence of tRNASer analogue directly demonstrates the role of SerRS· tRNASer interactions in SerRS affinity toward serine. It was also shown that noncovalent complex SerRS· tRNASer mischarges threonine to lesser extent than SerRS alone. These results confirm the importance of noncovalent interactions between SerRS and tRNASer in maintaining overall fidelity of aminoacylation reaction. [1] Gruić Sovulj, I. et al., J. Biol. Chem., 272 (1997) 32084-32091 [2] Lenhard, B. et al., J. Biol. Chem., 272 (1997) 1136-1141

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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