A Nutrient-Regulated Cyclic Diguanylate Phosphodiesterase Controls Clostridium difficile Biofilm and Toxin Production during Stationary Phase
A Nutrient-Regulated Cyclic Diguanylate Phosphodiesterase Controls Clostridium difficile Biofilm and Toxin Production during Stationary Phase
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DOI：
10.1128/iai.00347-17
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发表时间：
2017-09-01
影响因子：
3.1
通讯作者：
Tamayo, Rita
中科院分区：
文献类型：
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作者：
Purcell, Erin B.;McKee, Robert W.;Tamayo, Rita
信号分子环二胍酸盐（c-di-GMP）介导多种细菌对细胞外刺激的生理适应。控制c-di-GMP合成和降解的复杂代谢途径受到高度调控，但影响c-di-GMP信号传导的具体线索在很大程度上是未知的。在肠道病原体艰难梭菌中，c-di-GMP抑制鞭毛运动和毒素产生，促进菌毛依赖性生物膜的形成，但没有特定的生物学功能归因于任何单个c-di-GMP合成酶或磷酸二酯酶（PDEs）。在这里，我们报告了c-di-GMP PDE的功能和生化特性，PdcA是艰难梭菌630中37个确认或推测的c-di-GMP代谢蛋白中的1个。我们的研究表明，pdcA的转录受营养调节的转录调控因子CodY的控制，并在固定期相应增加。此外，PdcA PDE活性受GTP的变构调节，进一步将c-di-GMP水平与营养可用性联系起来。pdcA突变增加了生物膜的形成，减少了毒素的生物合成，但不影响游泳运动或细胞内c-di-GMP。对pdcA突变的转录反应分析表明，pdcA依赖性表型在固定期出现，与CodY的调控一致。这些结果表明，单个PDE基因的失活足以影响多种c-di-GMP依赖性表型，包括主要毒力因子的产生，并表明c-di-GMP信号传导与营养可利用性之间存在联系。
The signaling molecule cyclic diguanylate (c-di-GMP) mediates physiological adaptation to extracellular stimuli in a wide range of bacteria. The complex metabolic pathways governing c-di-GMP synthesis and degradation are highly regulated, but the specific cues that impact c-di-GMP signaling are largely unknown. In the intestinal pathogen Clostridium difficile, c-di-GMP inhibits flagellar motility and toxin production and promotes pilus-dependent biofilm formation, but no specific biological functions have been ascribed to any of the individual c-di-GMP synthases or phosphodiesterases (PDEs). Here, we report the functional and biochemical characterization of a c-di-GMP PDE, PdcA, 1 of 37 confirmed or putative c-di-GMP metabolism proteins in C. difficile 630. Our studies reveal that pdcA transcription is controlled by the nutrient-regulated transcriptional regulator CodY and accordingly increases during stationary phase. In addition, PdcA PDE activity is allosterically regulated by GTP, further linking c-di-GMP levels to nutrient availability. Mutation of pdcA increased biofilm formation and reduced toxin biosynthesis without affecting swimming motility or global intracellular c-di-GMP. Analysis of the transcriptional response to pdcA mutation indicates that PdcA-dependent phenotypes manifest during stationary phase, consistent with regulation by CodY. These results demonstrate that inactivation of this single PDE gene is sufficient to impact multiple c-di-GMPdependent phenotypes, including the production of major virulence factors, and suggest a link between c-di-GMP signaling and nutrient availability.