ABC-type amino acid uptake transporters Bgt and N-II of Anabaena sp. strain PCC 7120 share an ATPase subunit and are expressed in vegetative cells and heterocysts.
Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can fix N(2) in differentiated cells called heterocysts. Anabaena open reading frames alr4167 and alr3187 encode, respectively, an ATPase subunit, BgtA, and a composite protein bearing periplasmic substrate-binding and transmembrane domains, BgtB, of an ABC-type high-affinity basic amino acid uptake transporter (Bgt). Open reading frame alr4167 is clustered with open reading frames alr4164, alr4165 and alr4166 that encode a periplasmic substrate-binding protein, NatF, and transmembrane proteins NatG and NatH respectively. The NatF, NatG, NatH and BgtA proteins constitute an ABC-type uptake transporter for acidic and neutral polar amino acids (N-II). The Bgt and N-II transport systems thus share the ATPase subunit, BgtA. These transporters together with the previously characterized ABC-type uptake transporter for proline and hydrophobic amino acids (N-I) account for more than 98% of the amino acid transport activity exhibited by Anabaena sp. strain PCC 7120. In contrast to N-I that is expressed only in vegetative cells, the Bgt and N-II systems are present in both vegetative cells and heterocysts. Whereas Bgt is dispensable for diazotrophic growth, N-II appears to contribute together with N-I to the diazotrophic physiology of this cyanobacterium.
Pernil
Rafael
R
Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain.
Picossi
Silvia
S
Mariscal
Vicente
V
Herrero
Antonia
A
Flores
Enrique
E
D000251:Adenosine Triphosphatases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D026905:Amino Acid Transport Systems / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D017033:Anabaena / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D003227:Conjugation, Genetic; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation; D021122:Protein Subunits / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
D026905:Amino Acid Transport Systems; D000596:Amino Acids; D001426:Bacterial Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000251:Adenosine Triphosphatases