Analysis and expression of algL, which encodes alginate lyase in Pseudomonas syringae Pv. syringae

Pseudomonas syringae produces alginate, an exopolysaccharide that contributes to the virulence and epiphytic fitness of this phytopathogenic bacterium. P. syringae also produces the algL-encoded alginate lyase, which cleaves the alginate biopolymer via a beta-elimination reaction. The algL gene from P. syringae maps to a 1134 bp region within the alginate biosynthetic operon, and is similar to algL from Halomonas marina, P. aeruginosa, Azotobacter chroococcum, and A. vinelandii. algL from P. syringae was over expressed in Escherichia coli; two periplasmic forms of AlgL were overproduced (40 and 37 kDa). Both forms were enzymatically active and recognized by antibodies raised against AlgL from P. aeruginosa. Analysis of the regions flanking algL revealed significant homology to algX and algI, genes previously identified in the biosynthetic operon of other alginate-producing bacteria.