Stereoselective incorporation of an unsaturated isoleucine analogue into a protein expressed in E. coli.

The unsaturated amino acid 2-amino-3-methyl-4-pentenoic acid (E-Ile) was prepared in the form of its (2S,3S),(2R,3R) and (2S,3R),(2R,3S) stereoisomeric pairs. The translational activities of SS-E-Ile and SR-E-Ile were assessed in an E. coli strain rendered auxotrophic for isoleucine. SS-E-Ile was incorporated into the test protein mouse dihydrofolate reductase (mDHFR) in place of isoleucine at a rate of up to 72 %; SR-E-Ile yielded no conclusive evidence for incorporation. ATP/PPi exchange assays indicated that SS-E-Ile was activated by the isoleucyl-tRNA synthetase at a rate comparable to that characteristic of isoleucine; SR-E-Ile was activated approximately 100-times more slowly than SS-E-Ile.

Citation

Marissa L Mock, Thierry Michon, Jan C M van Hest, David A Tirrell. Stereoselective incorporation of an unsaturated isoleucine analogue into a protein expressed in E. coli. Chembiochem : a European journal of chemical biology. 2006 Jan;7(1):83-7

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PMID: 16397872

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