Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8.
Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8.
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(p)ppGpp 在胸膜肺炎放线杆菌 S8 活力和生物膜形成中的作用
DOI：
10.1371/journal.pone.0141501
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Wang C
中科院分区：
文献类型：
--
作者：
Li G;Xie F;Zhang Y;Bossé JT;Langford PR;Wang C
胸膜肺炎放线杆菌是一种革兰氏阴性杆菌，是猪胸膜肺炎的病原菌。当细菌遭遇营养饥饿时，依赖于RelA的(P)ppGpp介导的严格反应被激活。修饰核苷酸5‘-二磷酸鸟苷3’-二磷酸(PpGpp)和5‘-三磷酸鸟苷3’-二磷酸(PppGpp)在其他原核生物中是信号分子。为了研究(P)ppGpp在胸膜肺炎弧菌中的作用，我们建立了一株缺失(P)ppGpp合成酶relA的胸膜肺炎弧菌突变株S8ΔrelA，并对其体外表型进行了研究。S8ΔRelA在稳定期(饥饿状态)后不存活，仅以非伸展细胞的形式生长。与野生型(WT)菌株相比，S8ΔrelA突变体形成生物膜的能力增强。早期静止期培养的转录图谱显示，与WT株相比，S8ΔRelA共表达了405个细菌基因(其中380个上调，25个下调)。大多数上调的基因涉及核糖体结构和生物发生、氨基酸运输和代谢、翻译细胞壁/膜/被膜生物发生。结果表明，(P)ppGpp协调胸膜肺炎杆菌在饥饿条件下的生长、活力、形态、生物膜的形成和代谢能力。此外，S8ΔrelA不能利用某些糖，也不能产生与胸膜肺炎沙门氏菌毒力相关的尿素酶，提示(P)ppGpp可能直接或间接影响胸膜肺炎沙门氏菌在感染过程中的致病作用。综上所述，(P)ppGpp信号是调节胸膜肺炎沙门氏菌应激适应和毒力的调控网络的重要组成部分。
Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the cause of porcine pleuropneumonia. When the bacterium encounters nutritional starvation, the relA-dependent (p)ppGpp-mediated stringent response is activated. The modified nucleotides guanosine 5’-diphosphate 3’-diphosphate (ppGpp) and guanosine 5’-triphosphate 3’-diphosphate (pppGpp) are known to be signaling molecules in other prokaryotes. Here, to investigate the role of (p)ppGpp in A. pleuropneumoniae, we created a mutant A. pleuropneumoniae strain, S8ΔrelA, which lacks the (p)ppGpp-synthesizing enzyme RelA, and investigated its phenotype in vitro. S8ΔrelA did not survive after stationary phase (starvation condition) and grew exclusively as non-extended cells. Compared to the wild-type (WT) strain, the S8ΔrelA mutant had an increased ability to form a biofilm. Transcriptional profiles of early stationary phase cultures revealed that a total of 405 bacterial genes were differentially expressed (including 380 up-regulated and 25 down-regulated genes) in S8ΔrelA as compared with the WT strain. Most of the up-regulated genes are involved in ribosomal structure and biogenesis, amino acid transport and metabolism, translation cell wall/membrane/envelope biogenesis. The data indicate that (p)ppGpp coordinates the growth, viability, morphology, biofilm formation and metabolic ability of A. pleuropneumoniae in starvation conditions. Furthermore, S8ΔrelA could not use certain sugars nor produce urease which has been associated with the virulence of A. pleuropneumoniae, suggesting that (p)ppGpp may directly or indirectly affect the pathogenesis of A. pleuropneumoniae during the infection process. In summary, (p)ppGpp signaling represents an essential component of the regulatory network governing stress adaptation and virulence in A. pleuropneumoniae.