ILR1, AN AMIDOHYDROLASE THAT RELEASES ACTIVE INDOLE-3-ACETIC-ACID FROM CONJUGATES

In plants, the growth regulator indole-3-acetic acid (IAA) is found bo th free and conjugated to a variety of amino acids, peptides, and carb ohydrates. IAA conjugated to leucine has effects in Arabidopsis thalia na similar to those of free IAA. The ilr1 mutant is insensitive to exo genous IAA-Leu and was used to positionally clone the Arabidopsis ILR1 gene. ILR1 encodes a 48-kilodalton protein that cleaves IAA-amino aci d conjugates in vitro and is homologous to bacterial amidohydrolase en zymes. DNA sequences similar to that of ILR1 are found in other plant species.