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Research Paper |
Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel1
Author for correspondence: Zeev Barak. Tel: +972 8 6461713. Fax: +972 8 6461710. e-mail: barakz{at}bgumail.bgu.ac.il
The authors have developed a tool for the study of inhibitor-induced amino acid starvation in bacteria which exploits the phenomenon of translational frameshifting. The inhibition of acetohydroxyacid synthase II by the herbicide sulfometuron methyl (SMM) has complex effects on branched-chain amino acid biosynthesis. Experiments were done with Salmonella typhimurium containing a plasmid with an isoleucine codon in a shifty region, prone to translational frameshifting. SMM did not cause translational frameshifting in minimal medium under conditions that inhibit growth. A 20-fold higher concentration of SMM was required to cause starvation for isoleucine, e.g. in the presence of valine. This starvation was reflected in translational frameshifting correlated with inhibition of growth. These observations support the authors previous suggestions based on other techniques. The method used here could be generalized for the study of complex metabolic effects related to amino acids.
Keywords: acetohydroxyacid synthase, acetolactate synthase, branched-chain amino acids, sulfonylurea, amino acid biosynthesis
Abbreviations: AHAS, acetohydroxyacid synthase; ILHX, isoleucine hydroxamate; SMM, sulfometuron methyl
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