| Autor: |
Tretbar, Sandy, Neuenfeldt, Anne, Betat, Heike, Mörl, Mario |
| Předmět: |
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| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; 12/27/2011, Vol. 108 Issue 52, p21040-21045, 6p |
| Abstrakt: |
For efficient aminoacylation, tRNAs carry the conserved 3′-terminal sequence C-C-A, which is synthesized by highly specific tRNA nucleotidyltransferases (CCA-adding enzymes). In several prokaryotes, this function is accomplished by separate enzymes for CC- and A-addition. As A-adding enzymes carry an N-terminal catalytic core identical to that of CCA-adding enzymes, it is unclear why their activity is restricted. Here, it is shown that C-terminal deletion variants of A-adding enzymes acquire full and precise CCA-incorporating activity. The deleted region seems to be responsible for tRNA primer selection, restricting the enzyme's specificity to tRNAs ending with CC. The data suggest that A-adding enzymes carry an intrinsic CCA-adding activity that can be reactivated by the introduction of deletions in the C-terminal domain. Furthermore, a unique subtype of CCA-adding enzymes could be identified that evolved out of A-adding enzymes, suggesting that mutations and deletions in nucleotidyltransferases can lead to altered and even more complex activities, as a simple A-incorporation is converted into sequence-specific addition of C and A residues. Such activity-modifying events may have had an important role in the evolution of tRNA nucleotidyltransferases. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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