Influence of the Pseudomonas Quinolone Signal on Denitrification in Pseudomonas aeruginosa
Influence of the Pseudomonas Quinolone Signal on Denitrification in Pseudomonas aeruginosa
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DOI：
10.1128/jb.00968-08
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发表时间：
2008-10
影响因子：
3.2
通讯作者：
M. Toyofuku;N. Nomura;Eriko Kuno;Y. Tashiro;T. Nakajima;H. Uchiyama
中科院分区：
文献类型：
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作者：
M. Toyofuku;N. Nomura;Eriko Kuno;Y. Tashiro;T. Nakajima;H. Uchiyama
反硝化作用是一个被广泛研究的呼吸系统，在生物地球化学氮循环中也很重要。环境信号如氧和n -氧化物已被证明可以调节反硝化作用，尽管反硝化作用在细菌群落中是如何调节的仍不清楚。铜绿假单胞菌是一种普遍存在的细菌，通过细胞间信号控制许多基因。该细菌具有至少两个n -酰基-l-高丝氨酸内酯（AHL）信号。在我们之前的研究中，这些群体感应信号控制铜绿假单胞菌的反硝化作用。除了AHL信号外，第三种细胞间通讯信号，2-庚基-3-羟基-4-喹诺酮，被称为喹诺酮假单胞菌信号（PQS），已经被表征。在这项研究中，我们研究了PQS对反硝化的影响，以更深入地了解细菌群落的呼吸调节。PQS对铜绿假单胞菌的反硝化作用有抑制作用，PqsR和PqsE介导了部分抑制作用。反硝化酶活性测定表明，PQS可提高亚硝酸盐还原酶活性，抑制一氧化氮还原酶和硝酸盐呼吸链活性。这是第一个证明PQS影响酶活性的报告，表明这种影响不是铜绿假单胞菌所特有的。此外，当向添加了PQS的培养基中添加铁时，反硝化活性几乎恢复，这表明PQS的铁螯合性能影响了反硝化作用。因此，我们的数据表明PQS主要通过铁螯合调节反硝化。PQS对反硝化作用的影响与缺氧条件下诱导反硝化有关，提示其在有氧条件下控制反硝化作用。
ABSTRACT Denitrification is a well-studied respiratory system that is also important in the biogeochemical nitrogen cycle. Environmental signals such as oxygen and N-oxides have been demonstrated to regulate denitrification, though how denitrification is regulated in a bacterial community remains obscure. Pseudomonas aeruginosa is a ubiquitous bacterium that controls numerous genes through cell-to-cell signals. The bacterium possesses at least two N-acyl-l-homoserine lactone (AHL) signals. In our previous study, these quorum-sensing signals controlled denitrification in P. aeruginosa. In addition to the AHL signals, a third cell-to-cell communication signal, 2-heptyl-3-hydroxy-4-quinolone, referred to as the Pseudomonas quinolone signal (PQS), has been characterized. In this study, we examined the effect of PQS on denitrification to obtain more insight into the respiratory regulation in a bacterial community. Denitrification in P. aeruginosa was repressed by PQS, which was partially mediated by PqsR and PqsE. Measuring the denitrifying enzyme activities indicated that nitrite reductase activity was increased by PQS, whereas PQS inhibited nitric oxide reductase and the nitrate-respiratory chain activities. This is the first report to demonstrate that PQS influences enzyme activities, suggesting this effect is not specific to P. aeruginosa. Furthermore, when iron was supplied to the PQS-added medium, denitrifying activity was almost restored, indicating that the iron chelating property of PQS affected denitrification. Thus, our data indicate that PQS regulates denitrification primarily through iron chelation. The PQS effect on denitrification was relevant in a condition where oxygen was limited and denitrification was induced, suggesting its role in controlling denitrification where oxygen is present.