title: Nucleotide sequence and expression of the algE gene involved in alginate biosynthesis by Pseudomonas aeruginosa.
abstract: Alginate (Alg), a random polymer of mannuronic acid and glucuronic acid residues, is synthesized and secreted by Pseudomonas aeruginosa primarily during its infection of the lungs of cystic fibrosis patients. The molecular biology and biochemistry of the enzymatic steps leading to the production of the Alg precursor GDP-mannuronic acid have been elucidated, but the mechanism of polymer formation and export of Alg are not understood. We report the nucleotide sequence of a 2.4-kb DNA fragment containing the algE gene, previously designated alg76, encoding the AlgE protein (Mr 54,361) that is believed to be involved in these late steps of Alg biosynthesis. Expression of algE appears to occur from its own promoter. The promoter region contains several direct and inverted repeat sequences and shares structural similarity with promoters of several other alg genes from P. aeruginosa. In addition, the AlgE protein was overproduced from the tac promoter in P. aeruginosa. N-terminal amino acid sequence analysis showed that the polypeptide contains a signal peptide which is cleaved to form the mature protein during AlgE export from the cell cytoplasm.
authors.affiliation: Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago 60612.
authors.forename: L
authors.initials: L
authors.lastname: Chu
authors.forename: T B
authors.initials: TB
authors.lastname: May
authors.forename: A M
authors.initials: AM
authors.lastname: Chakrabarty
authors.forename: T K
authors.initials: TK
authors.lastname: Misra
mesh_terms: D000464:Alginates / Q000378:metabolism*; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D002238:Carbohydrate Epimerases; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression / Q000502:physiology; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D021382:Protein Sorting Signals / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics
chemical_list: D000464:Alginates; D001425:Bacterial Outer Membrane Proteins; D006603:Hexuronic Acids; D011135:Polysaccharides, Bacterial; D021382:Protein Sorting Signals; C064841:exopolysaccharide, Pseudomonas; D020723:Glucuronic Acid; D002238:Carbohydrate Epimerases; C086519:mannuronan c-5-epimerase