Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8

文献类型： 外文期刊

第一作者： Li, Gang

作者： Li, Gang;Xie, Fang;Zhang, Yanhe;Wang, Chunlai;Zhang, Yanhe;Bosse, Janine T.

作者机构：

期刊名称：PLOS ONE （ 影响因子：3.24； 五年影响因子：3.788 ）

ISSN： 1932-6203

年卷期： 2015 年 10 卷 10 期

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收录情况： SCI

摘要： 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, S8 Delta relA, which lacks the (p) ppGpp-synthesizing enzyme RelA, and investigated its phenotype in vitro. S8 Delta relA did not survive after stationary phase (starvation condition) and grew exclusively as non-extended cells. Compared to the wild-type (WT) strain, the S8 Delta relA 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 S8 Delta relA 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, S8 Delta relA 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.

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