Arabidopsis acetohydroxyacid synthase expressed in Escherichia coli is insensitive to the feedback inhibitors

Bijay Singh, Iwona Szamosi, J. Mark Hand, Rajeev Misra

Research output: Contribution to journalArticle

26 Scopus citations


Acetohydroxyacid synthase (AHAS), the first enzyme unique to the biosynthesis of isoleucine, leucine, and valine, is the target enzyme for several classes of herbicides. The AHAS gene from Arabidopsis thaliana, including the chloroplast transit peptide, was cloned into the bacterial expression plasmid pKK233-2. The resulting plasmid was used to transform an AHAS-deficient Escherichia coli strain MF2000. The growth of the MF2000 strain of E. coli was complemented by the functional expression of the Arabidopsis AHAS. The AHAS protein was processed to a molecular mass of 65 kilodaltons that was similar to the mature protein isolated from Arabidopsis seedlings. The AHAS activity extracted from the transformed E. coli cells was inhibited by imidazolinone and sulfonylurea herbicides. AHAS activity extracted from Arabidopsis is inhibited by valine and leucine; however, this activity was insensitive to these feedback inhibitors when extracted from the transformed E. coli.

Original languageEnglish (US)
Pages (from-to)812-816
Number of pages5
JournalPlant Physiology
Issue number3
StatePublished - Jan 1 1992
Externally publishedYes


ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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