scholarly journals Tunable translational control using site-specific unnatural amino acid incorporation in Escherichia coli

2015 ◽  
Author(s):  
Yusuke Kato
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Translational Control ◽  
Target Gene ◽  
Unnatural Amino Acid ◽  
Translational Efficiency ◽  
Amino Acid Incorporation ◽  
Amber Codon ◽  
Gene Transcripts ◽  
Tyrosine Concentration

Translation of target gene transcripts in Escherichia coli harboring UAG amber stop codons can be switched on by the amber-codon-specific incorporation of an exogenously supplied unnatural amino acid, 3-iodo-L-tyrosine. Here, we report that this translational switch can control the translational efficiency at any intermediate magnitude by adjustment of the 3-iodo-L-tyrosine concentration in the medium, as a tunable translational controller. The translational efficiency of a target gene reached maximum levels with 10-5 M 3-iodo-L-tyrosine, and intermediate levels were observed with suboptimal concentrations (approximately spanning a 2-log10 concentration range, 10-7 to 10-5 M). Such intermediate-level expression was also confirmed in individual bacteria.

scholarly journals Tunable translational control using site-specific unnatural amino acid incorporation in Escherichia coli

2015 ◽  
Author(s):  
Yusuke Kato
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Translational Control ◽  
Target Gene ◽  
Unnatural Amino Acid ◽  
Translational Efficiency ◽  
Amino Acid Incorporation ◽  
Amber Codon ◽  
Gene Transcripts ◽  
Tyrosine Concentration

Translation of target gene transcripts in Escherichia coli harboring UAG amber stop codons can be switched on by the amber-codon-specific incorporation of an exogenously supplied unnatural amino acid, 3-iodo-L-tyrosine. Here, we report that this translational switch can control the translational efficiency at any intermediate magnitude by adjustment of the 3-iodo-L-tyrosine concentration in the medium, as a tunable translational controller. The translational efficiency of a target gene reached maximum levels with 10-5 M 3-iodo-L-tyrosine, and intermediate levels were observed with suboptimal concentrations (approximately spanning a 2-log10 concentration range, 10-7 to 10-5 M). Such intermediate-level expression was also confirmed in individual bacteria.

How Optimized Is the Translational Machinery in Escherichia coli, Salmonella typhimurium and Saccharomyces cerevisiae?

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Xuhua Xia
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Salmonella Typhimurium ◽  
Codon Usage ◽  
Translational Efficiency ◽  
Square Root ◽  
Translational Machinery ◽  
Mutual Adaptation ◽  
Trna Species

Abstract The optimization of the translational machinery in cells requires the mutual adaptation of codon usage and tRNA concentration, and the adaptation of tRNA concentration to amino acid usage. Two predictions were derived based on a simple deterministic model of translation which assumes that elongation of the peptide chain is rate-limiting. The highest translational efficiency is achieved when the codon recognized by the most abundant tRNA reaches the maximum frequency. For each codon family, the tRNA concentration is optimally adapted to codon usage when the concentration of different tRNA species matches the square-root of the frequency of their corresponding synonymous codons. When tRNA concentration and codon usage are well adapted to each other, the optimal content of all tRNA species carrying the same amino acid should match the square-root of the frequency of the amino acid. These predictions are examined against empirical data from Escherichia coli, Salmonella typhimurium, and Saccharomyces cerevisiae.

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