Molecular cloning and characterization of an amidase from Arabidopsis thaliana capable of converting indole-3-acetamide into the plant growth hormone, indole-3-acetic acid

Phytochemistry. 2003 Feb;62(3):293-300. doi: 10.1016/s0031-9422(02)00563-0.


Acylamidohydrolases from higher plants have not been characterized or cloned so far. AtAMI1 is the first member of this enzyme family from a higher plant and was identified in the genome of Arabidopsis thaliana based on sequence homology with the catalytic-domain sequence of bacterial acylamidohydrolases, particularly those that exhibit indole-3-acetamide amidohydrolase activity. AtAMI1 polypeptide and mRNA are present in leaf tissues, as shown by immunoblotting and RT-PCR, respectively. AtAMI1 was expressed from its cDNA in enzymatically active form and exhibits substrate specificity for indole-3-acetamide, but also some activity against L-asparagine. The recombinant enzyme was characterized further. The results show that higher plants have acylamidohydrolases with properties similar to the enzymes of certain plant-associated bacteria such as Agrobacterium-, Pseudomonas- and Rhodococcus-species, in which these enzymes serve to synthesize the plant growth hormone, indole-3-acetic acid, utilized by the bacteria to colonize their host plants. As indole-3-acetamide is a native metabolite in Arabidopsis thaliana, it can no longer be ruled out that one pathway for the biosynthesis of indole-3-acetic acid involves indole-3-acetamide-hydrolysis by AtAMI1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidohydrolases / genetics*
  • Amidohydrolases / metabolism*
  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics*
  • Cloning, Molecular
  • Immunoblotting
  • Indoleacetic Acids / metabolism*
  • Molecular Sequence Data
  • Plant Growth Regulators / biosynthesis*
  • Plant Leaves / metabolism
  • Pseudomonas / genetics
  • RNA, Messenger / biosynthesis
  • Recombinant Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Rhizobium / genetics
  • Rhodococcus / genetics
  • Sequence Homology, Amino Acid
  • Substrate Specificity


  • Indoleacetic Acids
  • Plant Growth Regulators
  • RNA, Messenger
  • Recombinant Proteins
  • indoleacetic acid
  • indoleacetamide
  • Amidohydrolases