Contribution of the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems to Mg2+-induced gene regulation in Pseudomonas aeruginosa
Contribution of the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems to Mg2+-induced gene regulation in Pseudomonas aeruginosa
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DOI：
10.1128/jb.00053-06
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发表时间：
2006-06-01
影响因子：
3.2
通讯作者：
Hancock, R. E. W.
中科院分区：
文献类型：
--
作者：
McPhee, Joseph B.;Bains, Manjeet;Hancock, R. E. W.
当铜绿假单胞菌生长在二价阳离子限制的介质中时，它对阳离子抗菌肽和多粘菌素B产生抗药性。这种抗药性受Phop-PhoQ和PmrA-pmrB双组分调控系统的调节。为了进一步研究镁离子在铜绿假单胞菌中的调控作用，利用基因芯片转录图谱比较了在镁离子限制和镁离子充足条件下生长的野生型铜绿假单胞菌和在镁离子限制条件下生长的等基因Phop和pmrA突变株。在镁离子受限条件下(0.02 mM镁离子)，与在镁离子充足条件下(2 mM镁离子)生长的细菌相比，大约3%的铜绿假单胞菌基因有差异表达。只有一小部分受镁离子调控的基因通过Phop或PmrA进行调控。为了确定哪些基因受到直接调控，生物信息学搜索保守的结合基序，结合确认性逆转录酶PCR和凝胶移位启动子结合实验，结果表明很少有基因直接受到这些反应调节子的调控。研究发现，除了已知的oprH-Phop-PhoQ操纵子和pmrHFIJKLM-UGD操纵子外，编码小分子碱性蛋白的PA0921和PA1343基因还受到依赖于Phop的镁离子的调控。已知的PmrA调控基因的数量被扩大到包括PA1559-PA1560、PA4782-PA4781和feoAB操纵子，以及先前已知的PA4773-PA4775-pmrAB和pmrHFIJKLM-UGD操纵子。
When grown in divalent cation-limited medium, Pseudomonas aeruginosa becomes resistant to cationic antimicrobial peptides and polymyxin B. This resistance is regulated by the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems. To further characterize Mg2+ regulation in P. aeruginosa, microarray transcriptional profiling was conducted to compare wild-type P. aeruginosa grown under Mg2+-limited and Mg2+-replete conditions to isogenic phoP and pmrA mutants grown under Mg2+-limited conditions. Under Mg2+-limited conditions (0.02 mM Mg2+), approximately 3% of the P. aeruginosa genes were differentially expressed compared to the expression in bacteria grown under Mg2+-replete conditions (2 mM Mg2+). Only a modest subset of the Mg2+-regulated genes were regulated through either PhoP or PmrA. To determine which genes were directly regulated, a bioinformatic search for conserved binding motifs was combined with confirmatory reverse transcriptase PCR and gel shift promoter binding assays, and the results indicated that very few genes were directly regulated by these response regulators. It was found that in addition to the previously known oprH-phoP-phoQ operon and the pmrHFIJKLM-ugd operon, the PA0921 and PA1343 genes, encoding small basic proteins, were regulated by Mg2+ in a PhoP-dependent manner. The number of known PmrA-regulated genes was expanded to include the PA1559-PA1560, PA4782-PA4781, and feoAB operons, in addition to the previously known PA4773-PA4775-pmrAB and pmrHFIJKLM-ugd operons.