CLONING AND SEQUENCING OF AN ICE NUCLEATION ACTIVE GENE OF ERWINIA-UREDOVORA

An ice nucleation activity gene, named inaU, of the bacterium Erwinia uredovora KUIN-3 has been sequenced. This gene encodes a protein of 10 34 amino acid residues, and its expression product, inaU protein, has an 832-amino acid residue segment consisting of 52 repeats of closely related 16-amino acid motifs (R-domain), flanked by N- and C-terminal sequences (N- and C-domains, respectively). The primary structure of t he inaU protein is similar to those of the inaA, inaW, and inaZ gene p roducts of Erwinia ananas, Pseudomonas fluorescens, and Pseudomonas sy ringae, respectively, but is smaller than any of these products in ter ms of the size of the R-domain.