The absence of the Pseudomonas aeruginosa OprF protein leads to increased biofilm formation through variation in c-di-GMP level.
The absence of the Pseudomonas aeruginosa OprF protein leads to increased biofilm formation through variation in c-di-GMP level.
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DOI：
10.3389/fmicb.2015.00630
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发表时间：
2015
影响因子：
5.2
通讯作者：
Chevalier S
中科院分区：
文献类型：
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作者：
Bouffartigues E;Moscoso JA;Duchesne R;Rosay T;Fito-Boncompte L;Gicquel G;Maillot O;Bénard M;Bazire A;Brenner-Weiss G;Lesouhaitier O;Lerouge P;Dufour A;Orange N;Feuilloley MG;Overhage J;Filloux A;Chevalier S
OprF是属于假单胞菌属的细菌中的主要外膜孔蛋白。在以前的研究中，我们已经表明OprF是条件致病菌铜绿假单胞菌完全毒力表达所必需的。在这里，我们描述了这种关系的性质的分子见解，并报告说，OprF的情况下，导致增加的生物膜形成和生产的Pel胞外多糖。因此，在oprF突变体中，c-di-GMP（生物膜控制中的关键第二信使）的水平升高。通过降低该突变体中的c-di-GMP水平，生物膜形成和pel基因表达表型均恢复至野生型水平。我们进一步研究了对与生物膜生活方式相关的两种小RNA的影响，发现在oprF突变体中rsmZ而不是rsmY的表达增加，并且这以c-di-GMP依赖性方式发生。最后，细胞质外功能（ECF）σ因子AlgU和SigX在oprF突变体中显示出更高的活性水平。参与c-di-GMP代谢的SigX调节子的两个基因PA 1181和adcA（PA 4843）在oprF突变体中上调，部分解释了c-di-GMP水平的增加。我们假设OprF的缺乏导致细胞包膜应激，其激活SigX并由于adcA和PA 1181的更高表达而导致c-di-GMP水平升高。c-di-GMP水平又可以通过增加rsmZ sRNA水平和pel mRNA刺激Pel合成，从而影响Pel依赖性表型，如细胞聚集和生物膜形成。这项工作突出了OprF和c-di-GMP调节网络之间的联系，可能通过SigX（ECF）调节生物膜表型。
OprF is the major outer membrane porin in bacteria belonging to the Pseudomonas genus. In previous studies, we have shown that OprF is required for full virulence expression of the opportunistic pathogen Pseudomonas aeruginosa. Here, we describe molecular insights on the nature of this relationship and report that the absence of OprF leads to increased biofilm formation and production of the Pel exopolysaccharide. Accordingly, the level of c-di-GMP, a key second messenger in biofilm control, is elevated in an oprF mutant. By decreasing c-di-GMP levels in this mutant, both biofilm formation and pel gene expression phenotypes were restored to wild-type levels. We further investigated the impact on two small RNAs, which are associated with the biofilm lifestyle, and found that expression of rsmZ but not of rsmY was increased in the oprF mutant and this occurs in a c-di-GMP-dependent manner. Finally, the extracytoplasmic function (ECF) sigma factors AlgU and SigX displayed higher activity levels in the oprF mutant. Two genes of the SigX regulon involved in c-di-GMP metabolism, PA1181 and adcA (PA4843), were up-regulated in the oprF mutant, partly explaining the increased c-di-GMP level. We hypothesized that the absence of OprF leads to a cell envelope stress that activates SigX and results in a c-di-GMP elevated level due to higher expression of adcA and PA1181. The c-di-GMP level can in turn stimulate Pel synthesis via increased rsmZ sRNA levels and pel mRNA, thus affecting Pel-dependent phenotypes such as cell aggregation and biofilm formation. This work highlights the connection between OprF and c-di-GMP regulatory networks, likely via SigX (ECF), on the regulation of biofilm phenotypes.