FIG. 5.

l-Guluronate content of alginates produced by P. aeruginosa strains FRD1 (grey bars), FRD462 (black bars), and FRD1200 (white bars) expressing mutant forms of AlgG. l-Guluronate content is expressed as a percentage of wild-type FRD1 alginate. pMF54 is the vector control that lacks algG, and pMF55 is the vector control that expresses a wild-type copy of algG. (A) Mutant forms of AlgG where the mutations lie along the proposed epimerase catalytic face. These mutant proteins complement FRD1200 to the mucoid phenotype but do not have epimerase activity in either FRD1200 or FRD462. (B) AlgG mutant proteins that fail to complement epimerase activity in FRD462 and fail to complement FRD1200 to the mucoid phenotype. (C) AlgG mutant proteins containing deletions in the N-terminal region of the protein. Since some of the mutant proteins failed to complement FRD1200 to secrete alginate, the l-guluronate content of the alginate is not applicable (signified by N/A).