| Autor: |
Kaminska, Monika, Deniziak, Marzanna, Kerjan, Pierre, Barciszewski, Jan, Mirande, Marc |
| Předmět: |
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| Zdroj: |
EMBO Journal; 12/15/2000, Vol. 19 Issue 24, p6908-6917, 10p |
| Abstrakt: |
The cDNA encoding rice methionyl-tRNA synthetase was isolated. The protein exhibited a C-terminal polypeptide appended to a classical MetRS domain. This supplementary domain is related to endothelial monocyte activating polypeptide II (EMAPII), a cytokine produced in mammals after cleavage of p43, a component of the multisynthetase complex. It is also related to Arc1p and Trbp111, two tRNA binding proteins. We expressed rice MetRS and a derivative with a deletion of its EMAPII-like domain. Band-shift analysis showed that this extra-domain provides MetRS with non-specific tRNA binding properties. The EMAPII-like domain contributed a 10-fold decrease in KM for tRNA in the aminoacylation reaction catalyzed by the native enzyme, as compared with the C-terminally truncated MetRS. Consequently, the EMAPII domain provides MetRS with a better catalytic efficiency at the free tRNA concentration prevailing in vivo. This domain binds the acceptor minihelix of tRNAMet and facilitates its aminoacylation. These results suggest that the EMAPII module could be a relic of an ancient tRNA binding domain that was incorporated into primordial synthetases for aminoacylation of RNA minihelices taken as the ancestor of modern tRNA. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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