Iron interferes with quorum sensing-mediated cooperation in Pseudomonas aeruginosa by affecting the expression of ppyR and mexT, in addition to rhlR
Sun Feng, Li Na, Wang Lijia, Feng Huajun, Shen Dongsheng, Wang Meizhen,
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( Sun Feng ) - Zhejiang Gongshang University College of Environmental Science and Engineering
( Li Na ) - Zhejiang Gongshang University College of Environmental Science and Engineering
( Wang Lijia ) - Zhejiang Gongshang University College of Environmental Science and Engineering
( Feng Huajun ) - Zhejiang Gongshang University College of Environmental Science and Engineering
( Shen Dongsheng ) - Zhejiang Gongshang University College of Environmental Science and Engineering
( Wang Meizhen ) - Zhejiang Gongshang University College of Environmental Science and Engineering
Abstract
The stabilization of quorum sensing (QS) is vital for bacterial survival in various environments. Although the mechanisms of QS stabilization in certain conditions have been well studied, the impact of environmental factors has received much less attention. In this study, we show that the supplementation of 25 μM iron in competition experiments and 50 μM in evolution experiments to casein growth cultures significantly increased the possibility of population collapse by affecting elastase production. However, the expression of lasI and lasR remained constant regardless of iron concentration and hence this effect was not through interference with the LasIR circuit, which mainly regulates the secretion of elastase in Pseudomonas aeruginosa. However, the expression of rhlR was significantly inhibited by iron treatment, which could affect the production of elastase. Further, based on both reverse transcription quantitative polymerase chain reaction and gene knock-out assays, we show that iron inhibits the transcription of ppyR and enhances the expression of mexT, both of which decrease elastase production and correspondingly interfere with QS stabilization. Our findings show that environmental factors can affect the genes of QS circuits, interfering with QS stabilization. These findings are not only beneficial in understanding the mechanistic effect of iron on QS stabilization, but also demonstrate the complexity of QS stabilization by linking non-QS-related genes with QS traits.
키워드
Pseudomonas aeruginosa; iron; quorum sensing; elastase; cooperation
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