Characterization of the Erwinia carotovora peh gene and its product polygalacturonase.

The peh gene, encoding polygalacturonase (Peh), was identified in Erwinia carotovora strain EC and cloned in Escherichia coli. Recombinant Peh (re-Peh) was purified from E. coli strain 706 containing peh on a recombinant plasmid. The activity of the re-Peh protein is optimal at pH 5.5. The N-terminal and internal amino acid (aa) sequences of re-Peh were determined and compared to the aa sequence deduced from the nucleotide (nt) sequence of the cloned peh. The re-Peh has no similarity, based on either the nt sequences or the deduced aa sequences, to pectate lyases from the same Er. carotovora strain or other organisms.