Expression and fine structure of the gene encoding N-epsilon-(indole-3-acetyl)-L-lysine synthetase from Pseudomonas savastanoi

The gene encoding Nε-(indole-3-acetyl)-L-lysine synthetase, iaaL, from Pseudomonas savastanoi was localized within a 4.25-kilobase EcoRI fragment derived from pIAA1 of oleander strain EW 2009. Two open reading frames of 606 and 1188 nucleotides were identified upon sequencing, which directed the in vitro synthesis of Mr21,000 and Mr44,000 proteins. Expression of an open reading frame-2 subclone, pMON686, in Escherichia coli indicates that (indole-3-acetyl)-L-lysine synthetase is encoded solely by open reading frame-2. Hydrophobicity plots of the deduced open reading frame-1 protein suggest that it may be a membrane-bound protein, whereas the predicted iaaL gene product possesses considerable hydrophilic character, consistent with the demonstration of (indole-3-acetyl)-L-lysine synthetase activity in cell-free aqueous extracts. No nucleotide or protein homologies were found between iaaL and any sequences contained within the GenBank or National Biomedical Research Foundation data bases (April 13, 1989).