Expression of the phosphodiesterase BifA facilitating swimming motility is partly controlled by FliA in Pseudomonas putida KT2440.
Expression of the phosphodiesterase BifA facilitating swimming motility is partly controlled by FliA in Pseudomonas putida KT2440.
复制标题
恶臭假单胞菌 KT2440 中促进游泳运动的磷酸二酯酶 BifA 的表达部分受 FliA 控制
DOI：
10.1002/mbo3.402
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发表时间：
2017-02
期刊：
影响因子：
3.4
通讯作者：
Huang Q
中科院分区：
文献类型：
--
作者：
Xiao Y;Liu H;Nie H;Xie S;Luo X;Chen W;Huang Q
鞭毛介导的运动是许多细菌在营养耗尽和恶劣环境中生存的重要能力。通过过表达磷酸二酯酶BifA降低细胞内环二GMP（c-di-GMP）水平可促进鞭毛介导的运动，并诱导假单胞菌的运动性生活方式。调控bifA基因表达的机制研究较少。我们发现恶臭假单胞菌KT 2440中BifA的表达部分受鞭毛σ因子FliA（σ28）控制。FliA缺失导致bifA转录减少约两倍。5′ race分析显示bifA启动子区有两个转录起始点，上游分别为σ70和σ28启动子序列。σ28启动子区域的点突变降低了野生型KT 2440启动子的转录活性，但对fliA缺失突变体的转录活性没有影响。FliA过表达以BifA依赖的方式降低细胞内c-di-GMP水平，表明FliA能够调节细胞内c-di-GMP水平，并且BifA功能是调节所需的。此外，FliA过表达增强了野生型菌株的游泳能力，而对bifA突变体没有影响。我们的研究结果表明，FliA作为负调节因子，通过控制bifA的转录来调节c-di-GMP水平，以促进游泳运动。
Flagella‐mediated motility is an important capability of many bacteria to survive in nutrient‐depleted and harsh environments. Decreasing the intracellular cyclic di‐GMP (c‐di‐GMP) level by overexpression of phosphodiesterase BifA promotes flagellar‐mediated motility and induces planktonic lifestyle in Pseudomonas. The mechanism that regulates expression of bifA gene was poorly studied. Here we showed that expression of BifA was partly controlled by flagellar sigma factor FliA (σ28) in Pseudomonas putida KT2440. FliA deletion led to an approximately twofold decrease in transcription of bifA. 5′ race assay revealed two transcription start points in bifA promoter region, with the putative σ70 and σ28 promoter sequences upstream, respectively. Point mutation in σ28 promoter region reduced transcriptional activity of the promoter in wild‐type KT2440, but showed no influence on that in fliA deletion mutant. FliA overexpression decreased the intracellular c‐di‐GMP level in a BifA‐dependent way, suggesting that FliA was able to modulate the intracellular c‐di‐GMP level and BifA function was required for the modulation. Besides, FliA overexpression enhanced swimming ability of wild‐type strain, while made no difference to the bifA mutant. Our results suggest that FliA acts as a negative regulator to modulate the c‐di‐GMP level via controlling transcription of bifA to facilitate swimming motility.