title: High-affinity vanadate transport system in the cyanobacterium Anabaena variabilis ATCC 29413.
abstract: High-affinity vanadate transport systems have not heretofore been identified in any organism. Anabaena variabilis, which can fix nitrogen by using an alternative V-dependent nitrogenase, transported vanadate well. The concentration of vanadate giving half-maximum V-nitrogenase activity when added to V-starved cells was about 3 x 10(-9) M. The genes for an ABC-type vanadate transport system, vupABC, were found in A. variabilis about 5 kb from the major cluster of genes encoding the V-nitrogenase, and like those genes, the vupABC genes were repressed by molybdate; however, unlike the V-nitrogenase genes the vanadate transport genes were expressed in vegetative cells. A vupB mutant failed to grow by using V-nitrogenase unless high levels of vanadate were provided, suggesting that there was also a low-affinity vanadate transport system that functioned in the vupB mutant. The vupABC genes belong to a family of putative metal transport genes that include only one other characterized transport system, the tungstate transport genes of Eubacterium acidaminophilum. Similar genes are not present in the complete genomes of other bacterial strains that have a V-nitrogenase, including Azotobacter vinelandii, Rhodopseudomonas palustris, and Methanosarcina barkeri.
authors.affiliation: Department of Biology, University of Missouri-St. Louis, One University Blvd., St. Louis, MO 63121-4499, USA.
authors.forename: Brenda S
authors.initials: BS
authors.lastname: Pratte
authors.forename: Teresa
authors.initials: T
authors.lastname: Thiel
mesh_terms: D046870:Anabaena variabilis / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics; D003470:Culture Media; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009591:Nitrogenase; D016133:Polymerase Chain Reaction; D014638:Vanadates / Q000378:metabolism*
chemical_list: C090796:ATP-binding protein, bacteria; D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D026901:Membrane Transport Proteins; D014638:Vanadates; D009591:Nitrogenase