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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
Author(s) -
Pernil Rafael,
Picossi Silvia,
Mariscal Vicente,
Herrero Antonia,
Flores Enrique
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06107.x
Subject(s) - biology , periplasmic space , biochemistry , heterocyst , anabaena , amino acid , atp binding cassette transporter , open reading frame , protein subunit , transmembrane domain , atpase , transporter , peptide sequence , cyanobacteria , gene , genetics , enzyme , escherichia coli , bacteria
Summary 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.