BifA, a cyclic-di-GMP phosphodiesterase, inversely regulates biofilm formation and swarming motility by Pseudomonas aeruginosa PA14
BifA, a cyclic-di-GMP phosphodiesterase, inversely regulates biofilm formation and swarming motility by Pseudomonas aeruginosa PA14
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DOI：
10.1128/jb.00586-07
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发表时间：
2007-11-01
影响因子：
3.2
通讯作者：
O'Toole, George A.
中科院分区：
文献类型：
--
作者：
Kuchma, Sherry L.;Brothers, Kimberly M.;O'Toole, George A.
细胞内信号分子c-di-GMP(c-di-GMP)被证明影响细菌的行为，包括运动和生物膜的形成。我们报告了参与调控铜绿假单胞菌表面相关行为的基因PA4367的鉴定和特性。PA4367基因编码一个与c-di-GMP磷酸二酯酶活性相关的EAL结构域和一个与c-di-GMP合成双鸟苷环化酶活性相关的GGDEF结构域。PA4367基因的缺失导致集群运动的严重缺陷和超生物膜的表型；因此，我们将该基因命名为BIFA，用于生物膜的形成。我们发现BIFA定位于内膜，在生化研究中，纯化的BIFA蛋白在体外显示了磷酸二酯酶活性，但没有检测到二鸟苷环化酶活性。此外，对BIFA保守的EAL和GGDEF残基的突变分析表明，这两个结构域对观察到的磷酸二酯酶活性都很重要。与这些数据一致的是，Delta BIFA突变体表现出与野生型相比c-di-GMP细胞池的增加，以及由PEL基因座产生的多糖的合成增加。这种增加的多糖生产是Delta BIFA突变体形成的增强生物膜所必需的，但不会导致观察到的集群缺陷。Delta BIFA突变还导致鞭毛反转减少。基于对先前描述的sadB基因的上位性研究，我们认为BIFA在SadB的上游调控生物膜的形成和聚集。
The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in swarming motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner membrane and, in biochemical studies, that purified BifA protein exhibits phosphodiesterase activity in vitro but no detectable diguanylate cyclase activity. Furthermore, mutational analyses of the conserved EAL and GGDEF residues of BifA suggest that both domains are important for the observed phosphodiesterase activity. Consistent with these data, the Delta bifA mutant exhibits increased cellular pools of c-di-GMP relative to the wild type and increased synthesis of a polysaccharide produced by the pel locus. This increased polysaccharide production is required for the enhanced biofilm formed by the Delta bifA mutant but does not contribute to the observed swarming defect. The Delta bifA mutation also results in decreased flagellar reversals. Based on epistasis studies with the previously described sadB gene, we propose that BifA functions upstream of SadB in the control of biofilm formation and swarming.