Naslov
Seryl-tRNA syntheases: Structure, function and evolution across all three domains of life

Autori
Rokov Plavec, Jasmina ; Ročak, Sanda ; Gruić-Sovulj, Ita ; Landeka, Irena ; Lesjak, Sonja ; Jarić, Jelena ; Močibob, Marko ; Bilokapić, Silvija ; Weygand-Đurašević, Ivana

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

Izvornik
8. Hrvatski biološku kongres / Besendorfer, Višnja - Zagreb : Hrvatsko biološko društvo, 2003, 60-60

Skup
8. Hrvatski biološku kongres

Mjesto i datum
Zagreb, Hrvatska, 27.09.2003. - 02.10.2003

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
tRNASer ; seryl-tRNA synthetase ; evolution

Sažetak
Aminoacyl-tRNA synthetases (aaRS) are involved in protein biosynthesis by catalyzing specific aminoacylation of cognate tRNA. The availability of many genomic and cDNA sequences enabled us to clone the genes encoding seryl- tRNA synthetases (SerRS) from different taxonomic domains and to investigate the interaction of these enzymes with their cognate substrates through evolution. Accuracy of the aminoacylation reaction is very important since mistakes cause incorporation of the incorrect amino acid into proteins. Our kinetic studies have revealed that accurate seryl-tRNA synthesis in yeast and plants is accomplished via tRNA-assisted optimization of amino acid binding to the enzyme active site. A mechanism is proposed by which transient protein:RNA complex activates the cognate amino acid more efficiently and more specifically than the apoenzyme alone. Some eukaryotic aaRS participate in protein complexes that improve fidelity and efficacy of aminoacylation reactions. Using two-hybrid assay we have identified peroxin Pex21p as a protein that interacts with yeast SerRS. SerRS:Pex21p complex is more efficient in the aminoacylation reaction than SerRS alone. It has been proposed that C-terminal peptide of SerRS interacts with Pex21p, thereby stabilizing conformation of the active site, where tRNA binds. In plants, protein biosynthesis takes place in the cytosol, mitochondria and chloroplasts. Thus far, there have always been found two, not three, isoforms of the respective AARS, one being dual-targeted: either to cytosol/mitochondria or plastids/mitochondria. We have isolated two maize cDNAs encoding SerRS enzymes. One cDNA encodes a protein more similar to eukaryotic cytosolic counterparts. Based on the kinetic analysis, complementation of yeast gene disruption mutant in mitochondrial SerRS, analysis of the N-terminal signal sequence and phylogenetic analysis it is proposed that the other cDNA encodes a synthetase dual targeted to mitochondria and chloroplasts. Some methanogenic archaea contain atypical SerRSs that share very low sequence homology with other SerRSs. In search for identity elements in archaeal tRNAs, several hybrid tRNASer transcripts have been designed where domains of tRNASer from methanogenic archaea have been replaced with the ones from yeast tRNASer.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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