A chemosensory system that regulates biofilm formation through modulation of cyclic diguanylate levels
A chemosensory system that regulates biofilm formation through modulation of cyclic diguanylate levels
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DOI：
10.1073/pnas.0507170102
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发表时间：
2005-10-04
影响因子：
11.1
通讯作者：
Harwood, CS
中科院分区：
文献类型：
--
作者：
Hickman, JW;Tifrea, DF;Harwood, CS
铜绿假单胞菌引起慢性生物膜感染，其附着于表面和其他细胞的能力对于生物膜的形成和维持很重要。一个被称为wspF的基因突变，一个假定的化学感受信号转导操纵子的一部分，已被证明会导致细胞聚集和改变菌落形态。WspF表型取决于WspR的存在，WspR是被称为反应调节剂的信号转导蛋白家族的成员。很可能wspF突变的作用是通过磷酸化引起WspR的组成性激活。WspR含有已知催化细胞质信号分子环二鸟苷酸（c-diGMP）形成的GGDEF结构域。我们确定纯化的WspR在体外催化c-diGMP的形成，并且磷酸化刺激这种活性。我们观察到在wspF突变体中c-diGMP的细胞水平增加和生物膜形成增加。预测催化c-diGMP降解的蛋白质的表达逆转了wspF突变体的表型，并抑制了野生型细胞的生物膜起始，表明c-diGMP的存在是生物膜形成所必需的。转录组分析表明，至少560个基因的表达水平受到wspF缺失的影响。参与胞外多糖产生和生物膜形成的psi和pel操纵子在wspF突变体中以高水平表达。总之，这些数据表明wsp信号转导途径通过调节环二鸟苷酸水平来调节生物膜的形成。
Pseudomonas aeruginosa causes chronic biofilm infections, and its ability to attach to surfaces and other cells is important for biofilm formation and maintenance. Mutations in a gene called wspF, part of a putative chemosensory signal-transduction operon, have been shown to result in cell aggregation and altered colony morphology. The WspF phenotypes depend on the presence of WspR, which is a member of a family of signal transduction proteins known as response regulators. It is likely that the effect of the wspF mutation is to cause constitutive activation of WspR by phosphorylation. WspR contains a GGDEF domain known to catalyze formation of a cytoplasmic signaling molecule cyclic diguanylate (c-diGMP). We determined that purified WspR catalyzed the formation of c-diGMP in vitro and phosphorylation stimulated this activity. We observed increased cellular levels of c-diGMP and increased biofilm formation in a wspF mutant. Expression of a protein predicted to catalyze degradation of c-diGMP reversed the phenotypes of a wspF mutant and inhibited biofilm initiation by wild-type cells, indicating that the presence of c-diGMP is necessary for biofilm formation. A transcriptome analysis showed that expression levels of at least 560 genes were affected by a wspF deletion. The psi and pel operons, which are involved in exopolysaccharide production and biofilm formation, were expressed at high levels in a wspF mutant. Together, the data suggest that the wsp signal transduction pathway regulates biofilm formation through modulation of cyclic diguanylate levels.