α-Amylase (1,4-α-D-glucan glucanohydrolase, EC of apparent molecular mass 45 kDa was secreted by pv. grown in medium containing starch or maltose. We isolated its structural gene from a recombinant λ library and located it on a 2.7 kb DNA fragment. Nucleotide sequencing of the fragment revealed a potential ORF encoding a protein of 475 amino acid residues, including a potential signal sequence of 35 amino acids. The signal processing site was confirmed by N-terminal amino acid sequence analysis of the exported α-amylase. The deduced amino acid sequence of the mature protein is very similar to that of the α-amylase of . It also contains all four amino acid sequences highly conserved in the α-amylases from a wide range of organisms. Expression of the gene in was poor from its own promoter, but was enhanced by the upstream promoter on the vector. The α-amylase synthesized in was located in the periplasm.


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