Department of Biological Sciences, Binghamton University, Binghamton, New York 13902, USA.
J Bacteriol. 2010 Oct;192(20):5275-88. doi: 10.1128/JB.00387-10. Epub 2010 Jul 23.
The formation of biofilms by the opportunistic pathogen Pseudomonas aeruginosa is a developmental process governed by a novel signal transduction system composed of three two-component regulatory systems (TCSs), BfiSR, BfmSR, and MifSR. Here, we show that BfiSR-dependent arrest of biofilm formation coincided with reduced expression of genes involved in virulence, posttranslational/transcriptional modification, and Rhl quorum sensing but increased expression of rhlAB and the small regulatory RNAs rsmYZ. Overexpression of rsmZ, but not rsmY, coincided with impaired biofilm development similar to inactivation of bfiS and retS. We furthermore show that BfiR binds to the 5' untranslated region of cafA encoding RNase G. Lack of cafA expression coincided with impaired biofilm development and increased rsmYZ levels during biofilm growth compared to the wild type. Overexpression of cafA restored ΔbfiS biofilm formation to wild-type levels and reduced rsmZ abundance. Moreover, inactivation of bfiS resulted in reduced virulence, as revealed by two plant models of infection. This work describes the regulation of a committed biofilm developmental step following attachment by the novel TCS BfiSR through the suppression of sRNA rsmZ via the direct regulation of RNase G in a biofilm-specific manner, thus underscoring the importance of posttranscriptional mechanisms in controlling biofilm development and virulence.
机会性病原体铜绿假单胞菌生物膜的形成是一个由三个双组分调控系统（TCSs），BfiSR、BfmSR 和 MifSR 组成的新型信号转导系统控制的发育过程。在这里，我们表明 BfiSR 依赖性生物膜形成的停滞与毒力、翻译后/转录修饰和 Rhl 群体感应相关基因的表达减少，但 rhlAB 和小调控 RNA rsmYZ 的表达增加有关。与 bfiS 和 retS 的失活相似，rsmZ 的过表达而非 rsmY 的过表达与生物膜发育受损同时发生。我们还表明 BfiR 结合到编码 RNase G 的 cafA 的 5'非翻译区。与野生型相比，cafA 表达缺失导致生物膜发育受损和生物膜生长过程中 rsmYZ 水平增加。cafA 的过表达将 ΔbfiS 生物膜形成恢复到野生型水平，并降低了 rsmZ 的丰度。此外，bfiS 的失活导致毒力降低，这在两种植物感染模型中得到了揭示。这项工作描述了通过直接调控生物膜特异性 RNase G 来抑制 sRNA rsmZ，从而在附着后通过新型 TCS BfiSR 对特定的生物膜发育步骤进行调控，从而强调了转录后机制在控制生物膜发育和毒力方面的重要性。
