title: Salt adaptation in Acinetobacter baylyi: identification and characterization of a secondary glycine betaine transporter.
abstract: Members of the genus Acinetobacter are well known for their metabolic versatility that allows them to adapt to different ecological niches. Here, we have addressed how the model strain Acinetobacter baylyi copes with different salinities and low water activities. A. baylyi tolerates up to 900 mM sodium salts and even higher concentrations of potassium chloride. Growth at high salinities was better in complex than in mineral medium and addition of glycine betaine stimulated growth at high salinities in mineral medium. Cells grown at high salinities took up glycine betaine from the medium. Uptake of glycine betaine was energy dependent and dependent on a salinity gradient across the membrane. Inspection of the genome sequence revealed two potential candidates for glycine betaine transport, both encoding potential secondary transporters, one of the major facilitator superfamily (MFS) class (ACIAD2280) and one of the betaine/choline/carnitine transporter (BCCT) family (ACIAD3460). The latter is essential for glycine betaine transport in A. baylyi. The broad distribution of ACIAD3460 homologues indicates the essential role of secondary transporters in the adaptation of Acinetobacter species to osmotic stress.
authors.affiliation: Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt am Main, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Sand
authors.forename: Veronique
authors.initials: V
authors.lastname: de Berardinis
authors.forename: Ana
authors.initials: A
authors.lastname: Mingote
authors.forename: Helena
authors.initials: H
authors.lastname: Santos
authors.forename: Stephan
authors.initials: S
authors.lastname: Göttig
authors.forename: Volker
authors.initials: V
authors.lastname: Müller
authors.forename: Beate
authors.initials: B
authors.lastname: Averhoff
mesh_terms: D000150:Acinetobacter / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001622:Betaine / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D050485:GABA Plasma Membrane Transport Proteins; D016680:Genome, Bacterial; D011189:Potassium Chloride / Q000378:metabolism; D054712:Salinity; D012965:Sodium Chloride / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; C072207:betaine plasma membrane transport proteins; D001622:Betaine; D012965:Sodium Chloride; D011189:Potassium Chloride