Nitric Oxide Signaling in Pseudomonas aeruginosa Biofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-GMP Levels, and Enhanced Dispersal
Nitric Oxide Signaling in Pseudomonas aeruginosa Biofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-GMP Levels, and Enhanced Dispersal
复制标题
DOI：
10.1128/jb.00975-09
复制
发表时间：
2009-12-01
影响因子：
3.2
通讯作者：
Kjelleberg, Staffan
中科院分区：
文献类型：
--
作者：
Barraud, Nicolas;Schleheck, David;Kjelleberg, Staffan
生物膜中的细菌经常经历活跃的扩散事件，并恢复到自由游泳的浮游状态，以完成生物膜的生命周期。信号分子一氧化氮(NO)以前被发现在低浓度、无毒的条件致病菌铜绿假单胞菌中触发生物膜扩散(N.Barraud，D.J.Hassett，S.H.Hwang，S.A.莱斯，S.Kjelleberg和J.S.Webb，J.细菌素)。188：7344-7353,2006)。进一步研究表明，NO可增加细胞的运动能力和对抗菌剂的敏感性。最近，大量研究表明，特定的磷酸二酯酶(PDE)加速降解次要信使环二GMP(c-di-GMP)，从而触发真细菌的浮游生长模式。在这项研究中，通过进行(I)PDE抑制剂研究，(Ii)酶法检测PDE活性，(Iii)直接定量细胞内c-di-GMP水平，研究了NO和c-di-GMP信号之间的潜在联系。这些结果表明，c-di-GMP信号在触发NO诱导的生物膜扩散事件中起作用，因为扩散需要PDE活性，而NO的加入刺激了PDE，并导致铜绿假单胞菌细胞内c-di-GMP水平的伴随下降。此外，基因表达研究表明，铜绿假单胞菌生物膜对低水平、无毒的NO有全球性的反应，包括运动和能量代谢相关基因的上调，以及粘附素和毒力因子的下调。最后，候选基因的定点突变和相应突变菌株的生理特性表明，趋化转导基因BdlA参与了NO诱导的生物膜扩散反应。
Bacteria in biofilms often undergo active dispersal events and revert to a free-swimming, planktonic state to complete the biofilm life cycle. The signaling molecule nitric oxide (NO) was previously found to trigger biofilm dispersal in the opportunistic pathogen Pseudomonas aeruginosa at low, nontoxic concentrations (N. Barraud, D. J. Hassett, S. H. Hwang, S. A. Rice, S. Kjelleberg, and J. S. Webb, J. Bacteriol. 188: 7344-7353, 2006). NO was further shown to increase cell motility and susceptibility to antimicrobials. Recently, numerous studies revealed that increased degradation of the secondary messenger cyclic di-GMP (c-di-GMP) by specific phosphodiesterases (PDEs) triggers a planktonic mode of growth in eubacteria. In this study, the potential link between NO and c-di-GMP signaling was investigated by performing (i) PDE inhibitor studies, (ii) enzymatic assays to measure PDE activity, and (iii) direct quantification of intracellular c-di-GMP levels. The results suggest a role for c-di-GMP signaling in triggering the biofilm dispersal event induced by NO, as dispersal requires PDE activity and addition of NO stimulates PDE and induces the concomitant decrease in intracellular c-di-GMP levels in P. aeruginosa. Furthermore, gene expression studies indicated global responses to low, nontoxic levels of NO in P. aeruginosa biofilms, including upregulation of genes involved in motility and energy metabolism and downregulation of adhesins and virulence factors. Finally, site-directed mutagenesis of candidate genes and physiological characterization of the corresponding mutant strains uncovered that the chemotaxis transducer BdlA is involved in the biofilm dispersal response induced by NO.