title: Overproduction and assay of Pseudomonas aeruginosa phosphomannose isomerase.
abstract: Phosphomannose isomerase activity was undetectable in extracts of mucoid (alginate-producing) Pseudomonas aeruginosa. When a P. aeruginosa gene previously shown to complement an alginate-negative mutant was overexpressed under the control of the tac promoter in the broad-host-range controlled-expression vector pMMB22, phosphomannose isomerase activity could be measured in extracts of P. aeruginosa and in a manA (phosphomannose isomerase-negative) mutant of Escherichia coli. P. aeruginosa extracts containing induced levels of enzyme were shown to interconvert fructose 6-phosphate and mannose 6-phosphate. A 56,000-dalton polypeptide was visualized on sodium dodecyl sulfate-polyacrylamide gels after induction in both hosts. When RNA-DNA dot- blot hybridization analysis was used, transcription of algA, the gene coding for P. aeruginosa phosphomannose isomerase, was not measurable from the chromosomes of either mucoid or nonmucoid P. aeruginosa. However, a high level of algA transcription was detected after expression of algA under tac promoter control in pMMB22.
mesh_terms: D000464:Alginates / Q000096:biosynthesis; D002238:Carbohydrate Epimerases / Q000096:biosynthesis*; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D008359:Mannose-6-Phosphate Isomerase / Q000032:analysis / Q000096:biosynthesis*; D008970:Molecular Weight; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000464:Alginates; D012329:RNA, Bacterial; D012333:RNA, Messenger; D002238:Carbohydrate Epimerases; D008359:Mannose-6-Phosphate Isomerase