Isolation and characterization of an unusual 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase gene from Enterobacter cloacae UW4

A genomic library of the 1-aminocyclopropane-1-carboxylic acid (ACC) deamin ase-containing plant growth-promoting bacterium Enterobacter cloacae UW4 in pUC19 in Escherichia coli was screened for the ability to utilize ACC as a sole source of nitrogen. One of the clones that was isolated contained a p lasmid with an insert of approximately 0.8 kb that conferred ACC deaminase activity. Sequence analysis revealed that this DNA fragment contains an ope n-reading frame of 696 nucleotides predicted to encode a protein of 232 ami no acids, a member of the amidohydrolase protein superfamily, i.e., a deami nase that contains a mononuclear or binuclear metal center as compared to t he canonical ACC deaminase which contains pyridoxal phosphate as a co-facto r.