Lehrstuhl für Biologie der Mikroorganismen Medizinisches Proteom-Center, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Mol Microbiol. 2011 Apr;80(2):492-506. doi: 10.1111/j.1365-2958.2011.07589.x. Epub 2011 Mar 3.
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.
受伤的植物会激活复杂的防御程序以应对根瘤农杆菌。它们合成非蛋白氨基酸γ-氨基丁酸（GABA），刺激群体感应信号 N-(3-氧代-辛酰基)高丝氨酸内酯的降解。GABA 通过依赖于周质结合蛋白 Atu2422 的 ABC 转运体进入根瘤农杆菌。我们证明 atu2422 和另外两个 ABC 转运体基因的表达受保守的小 RNA (sRNA) AbcR1（ABC 调节剂）下调。AbcR1 与另一个序列和结构相似的 sRNA 串联编码。这两个 sRNA 在静止期积累，但只有 AbcR1 的缺失导致 Atu2422 的显著积累和 GABA 摄取增加。AbcR1 通过掩盖其 Shine-Dalgarno 序列来抑制 atu2422 翻译的起始，从而降低 atu2422 转录本的稳定性。这是第一个描述的细菌 sRNA 控制植物产生的信号分子的摄取。鉴于类似的 sRNA 和 ABC 转运体基因存在于各种根瘤菌科和布鲁氏菌中，这种 sRNA 介导的控制很可能影响许多宿主-微生物相互作用。
