Strehmel Janine, Neidig Anke, Nusser Michael, Geffers Robert, Brenner-Weiss Gerald, Overhage Joerg
Appl Environ Microbiol. 2015 Feb;81(4):1274-85. doi: 10.1128/AEM.02832-14.
Pseudomonas aeruginosa is an opportunistic human pathogen that is able to sense and adapt to numerous environmental stimuli by the use of transcriptional regulators, including two-component regulatory systems. In this study, we demonstrate that the sensor kinase PA4398 is involved in the regulation of swarming motility and biofilm formation in P. aeruginosa PA14. APA4398 mutant strain was considerably impaired in swarming motility, while biofilm formation was increased by approximately 2-fold. The PA4398 mutant showed no changes in growth rate, rhamnolipid synthesis, or the production of the Pel exopolysaccharide but exhibited levels of the intracellular second messenger cyclic dimeric GMP (c-di-GMP) 50% higher than those in wild-type cells. The role of PA4398 in gene regulation was investigated by comparing the PA4398 mutant to the wildtype strain by using microarray analysis, which demonstrated that 64 genes were up- or downregulated more than 1.5-fold (P<0.05) under swarming conditions. In addition, more-sensitive real-time PCR studies were performed on genes known to be involved in c-di-GMP metabolism. Among the dysregulated genes were several involved in the synthesis and degradation of c-di-GMP or in the biosynthesis, transport, or function of the iron-scavenging siderophores pyoverdine and pyochelin, in agreement with the swarming phenotype observed. By analyzing additional mutants of selected pyoverdine- and pyochelin-related genes,we were able to show that not only pvdQ but also pvdR, fptA, pchA, pchD, and pchH are essential for the normal swarming behavior of P. aeruginosa PA14 and may also contribute to the swarming-deficient phenotype of the PA4398 mutant in addition to elevated c-di-GMP levels.
铜绿假单胞菌是一种机会性人类病原体，能够通过使用转录调节因子（包括双组分调节系统）来感知并适应多种环境刺激。在本研究中，我们证明传感激酶PA4398参与了铜绿假单胞菌PA14群体游动性和生物膜形成的调控。PA4398突变株的群体游动性显著受损，而生物膜形成增加了约2倍。PA4398突变体在生长速率、鼠李糖脂合成或Pel胞外多糖的产生方面没有变化，但细胞内第二信使环二聚体鸟苷酸（c-di-GMP）的水平比野生型细胞高50%。通过使用微阵列分析将PA4398突变体与野生型菌株进行比较，研究了PA4398在基因调控中的作用，结果表明在群体游动条件下，有64个基因的上调或下调超过1.5倍（P<0.05）。此外，对已知参与c-di-GMP代谢的基因进行了更灵敏的实时PCR研究。失调的基因中有几个参与了c-di-GMP的合成和降解，或参与了铁载体绿脓菌素和焦磷酸菌素的生物合成、运输或功能，这与观察到的群体游动表型一致。通过分析选定的绿脓菌素和焦磷酸菌素相关基因的其他突变体，我们能够表明，除了c-di-GMP水平升高外，不仅pvdQ，而且pvdR、fptA、pchA、pchD和pchH对于铜绿假单胞菌PA14的正常群体游动行为也是必不可少的，并且可能也导致了PA4398突变体的群体游动缺陷表型。
