The production of a mucoid capsular material, alginate, by P. aeruginosa is important for persistence of the pathogen in patients with cystic fibrosis. In previous work, Dr. Schiller demonstrated that alginate producing strains of P. aeruginosa also express alginate lyase, an enzyme that depolymerizes the mucopolysaccharides. Alginate lyase cleaves the 1-4 glycosidic linkage of L-guluronic-D-mannuronic polymers. The gene for alginate lyase (algL) was cloned and sequenced and mapped within an operon that contains the biosynthetic genes for alginate synthesis. algL is co-ordinately regulated with the alginate biosynthetic genes, indicating that this protein may serve a role in alginate synthesis or transport. The goals of this proposal are to define the role of algL and an upstream gene termed algX, in alginate synthesis, secretion, or chemical structure; to biochemically purify and characterize the activity of AlgL; to perform a structure/function analysis of AlgL; and to determine if AlgL is associated with other proteins. The long term objectives are to understand the mechanism of alginate synthesis and to contribute additional information regarding the activities of AlgL. This information may be useful in the rational design of enzyme inhibitors or the use of alginate lyase in the disruption of capsular material surrounding and protecting P. aeruginosa microcolonies from host immune responses and antibiotic treatment.