Characterization of alginate lyase from Pseudomonas syringae pv. syringae

The gene encoding alginate lyase (algL) in Pseudomonas syringae pv. syringa e was cloned, sequenced, and overexpressed in Escherichia coli. Alginate ly ase activity was optimal when the pH was 7.0 and when assays were conducted at 42 degrees C in the presence of 0.2 M NaCl. In substrate specificity st udies, AlgL from P. syringae showed a preference for deacetylated polymannu ronic acid. Sequence alignment with other alginate lyases revealed conserve d regions within AlgL likely to be important for the structure and/or funct ion of the enzyme. Site-directed mutagenesis of histidine and tryptophan re sidues at positions 204 and 207, respectively, indicated that these amino a cids are critical for lyase activity.