title: Small RNA-mediated control of the Agrobacterium tumefaciens GABA binding protein.
abstract: Wounded plants activate a complex defence programme in response to Agrobacterium tumefaciens. They synthesize the non-proteinogenic amino acid γ-aminobutyric acid (GABA), which stimulates degradation of the quorum sensing signal N-(3-oxo-octanoyl) homoserine lactone. GABA is transported into A. tumefaciens via an ABC transporter dependent on the periplasmic binding protein Atu2422. We demonstrate that expression of atu2422 and two other ABC transporter genes is downregulated by the conserved small RNA (sRNA) AbcR1 (for ABC regulator). AbcR1 is encoded in tandem with another sRNA, which is similar in sequence and structure. Both sRNAs accumulate during stationary phase but only the absence of AbcR1 resulted in significant accumulation of Atu2422 and increased GABA import. AbcR1 inhibits initiation of atu2422 translation by masking its Shine-Dalgarno sequence and thereby reduces stability of the atu2422 transcript. It is the first described bacterial sRNA that controls uptake of a plant-generated signalling molecule. Given that similar sRNAs and ABC transporter genes are present in various Rhizobiaceae and in Brucella, it is likely that such sRNA-mediated control impacts a number of host-microbe interactions.
authors.affiliation: Lehrstuhl für Biologie der Mikroorganismen Medizinisches Proteom-Center, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Wilms
authors.forename: Björn
authors.initials: B
authors.lastname: Voss
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
authors.forename: Lars I
authors.initials: LI
authors.lastname: Leichert
authors.forename: Franz
authors.initials: F
authors.lastname: Narberhaus
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis*; D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D034741:RNA, Small Interfering / Q000378:metabolism*; D016415:Sequence Alignment; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D034741:RNA, Small Interfering; D005680:gamma-Aminobutyric Acid