SEQUENCE OF THE ALGL GENE OF PSEUDOMONAS-AERUGINOSA AND PURIFICATION OF ITS ALGINATE LYASE PRODUCT

The alginate lyase-encoding gene (algL) of Pseudomonas aeruginosa was localized to a 1.7-kb EcoRI-XbaI fragment within the alginate biosynth etic gene cluster at 34 minutes on the chromosome. The nucleotide sequ ence of this DNA fragment revealed an ORF encoding a protein of M(r) 4 0 885 which is transcribed in the same orientation as the other alg ge nes within the biosynthetic gene cluster. The predicted protein has a potential N-terminal signal peptide which is consistent with its propo sed periplasmic location. The AlgL protein was overproduced in Escheri chia coli and purified. The purified protein was shown to have alginat e lyase activity. In addition, an algL insertion mutant of the mucoid P. aeruginosa 8830 was constructed. This mutant (alm 1) had a nonmucoi d phenotype due to a polar effect on the transcription of an essential alg gene, algA. Thus, the algL gene is located within a region of the alginate biosynthetic gene cluster that appears to be non-essential f or alginate production.