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Transplantation of a tyrosine editing domain into a tyrosyl-tRNA synthetase variant enhances its specificity for a tyrosine analog.

Transplantation of a tyrosine editing domain into a tyrosyl-tRNA synthetase variant enhances its specificity for a tyrosine analog.

Authors :
Oki K
Sakamoto K
Kobayashi T
Sasaki HM
Yokoyama S
Source :
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2008 Sep 09; Vol. 105 (36), pp. 13298-303. Date of Electronic Publication: 2008 Sep 02.
Publication Year :
2008

Abstract

To guarantee specific tRNA and amino acid pairing, several aminoacyl-tRNA synthetases correct aminoacylation errors by deacylating or "editing" misaminoacylated tRNA. A previously developed variant of Escherichia coli tyrosyl-tRNA synthetase (iodoTyrRS) esterifies or "charges" tRNA(Tyr) with a nonnatural amino acid, 3-iodo-l-tyrosine, and with l-tyrosine less efficiently. In the present study, the editing domain of phenylalanyl-tRNA synthetase (PheRS) was transplanted into iodoTyrRS to edit tyrosyl-tRNA(Tyr) and thereby improve the overall specificity for 3-iodo-l-tyrosine. The beta-subunit fragments of the PheRSs from Pyrococcus horikoshii and two bacteria were tested for editing activity. The isolated B3/4 editing domain of the archaeal PheRS, which was exogenously added to the tyrosylation reaction with iodoTyrRS, efficiently reduced the production of tyrosyl-tRNA(Tyr). In addition, the transplantation of this domain into iodoTyrRS at the N terminus prevented tyrosyl-tRNA(Tyr) production most strongly among the tested fragments. We next transplanted this archaeal B3/4 editing domain into iodoTyrRS at several internal positions. Transplantation into the connective polypeptide in the Rossmann-fold domain generated a variant that efficiently charges tRNA(Tyr) with 3-iodo-l-tyrosine, but hardly produces tyrosyl-tRNA(Tyr). This variant, iodoTyrRS-ed, was used, together with an amber suppressor derived from tRNA(Tyr), in a wheat germ cell-free translation system and incorporated 3-iodo-l-tyrosine, but not l-tyrosine, in response to the amber codon. Thus, the editing-domain transplantation achieved unambiguous pairing between the tRNA and the nonnatural amino acid in an expanded genetic code.

Details

Language :
English
ISSN :
1091-6490
Volume :
105
Issue :
36
Database :
MEDLINE
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
18765802
Full Text :
https://doi.org/10.1073/pnas.0803531105