The Azotobacter vinelandii alg8 and alg44 genes are essential for alginate synthesis and can be transcribed from an algD-independent promoter.
A 2.8-kb DNA region, located immediately downstream of algD, contains the A. vinelandii alg8 and alg44 genes, whose sequences are highly homologous to those of the corresponding Pseudomonas aeruginosa genes. These genes occur on a transcript that does not include algD, and are transcribed from a promoter different from that transcribing algD; this is the fourth promoter described within the alginate biosynthetic gene cluster. alg8 and alg44 mutants were constructed and shown to be completely impaired in alginate production. Alg8 shares 28.20% identity and 38.09% similarity to Azorhizobium caulinodans NodC, a glycosyl transferase catalyzing the formation of beta-1,4 linkages. A topological model is predicted, which supports the idea of Alg8 being the polymerase responsible for alginate synthesis.
Mejía-Ruíz
H
H
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos.
Guzmán
J
J
Moreno
S
S
Soberón-Chávez
G
G
Espín
G
G
D000464:Alginates / Q000378:metabolism*; D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002237:Carbohydrate Dehydrogenases / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D020723:Glucuronic Acid; D016695:Glycosyltransferases / Q000737:chemistry / Q000235:genetics; D006603:Hexuronic Acids; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D017433:Protein Structure, Secondary; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000235:genetics*
C085500:Alg44 protein, Pseudomonas aeruginosa; C085499:Alg8 protein, Pseudomonas aeruginosa; D000464:Alginates; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D020723:Glucuronic Acid; D002237:Carbohydrate Dehydrogenases; C020562:GDPmannose dehydrogenase; D016695:Glycosyltransferases