Regulation of Serratia marcescens ompF and ompC porin genes in response to osmotic stress, salicylate, temperature and pH
Regulation of Serratia marcescens ompF and ompC porin genes in response to osmotic stress, salicylate, temperature and pH
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DOI：
10.1099/mic.0.28428-0
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发表时间：
2006-02-01
期刊：
影响因子：
2.8
通讯作者：
Worobec, EA
中科院分区：
文献类型：
--
作者：
Begic, S;Worobec, EA
粘质沙雷氏菌是一种革兰氏阴性肠杆菌，由于其高度的天然耐药性，已成为一种重要的机会致病菌。造成这种天然抗生素耐药性的一个因素是外膜通透性降低，这在一定程度上是由OMPC和OmpF孔蛋白控制的。OmpF的表达受MICF调控，MICF是一种编码在OMPC基因上游的RNA转录本，它与OmpF转录本杂交以抑制其翻译。利用β-半乳糖苷酶报告基因融合技术，研究了5、8和10%蔗糖、1、5和8 mM水杨酸盐以及不同pH和温度对粘质链霉菌porin基因表达和MICF表达的调控。β-半乳糖苷酶活性测定表明，较低的生长温度(28℃)、较碱性的pH(PH 8)以及不含蔗糖和水杨酸盐都能诱导OmpF基因的转录，而OMPC的诱导则在较高的生长温度(42℃)、酸性pH(PH 6)和蔗糖(110%)和水杨酸盐(8 MM)的最大浓度下才被刺激。此外，在多种条件下，温度的影响最大，其次是pH。在本研究中，发现MICF调节机制在OmpF和OMPC基因的渗透调节中不起作用，而MICF在水杨酸盐存在、高生长温度和低pH条件下抑制OmpF的表达。
Serratia marcescens is a Gram-negative enterobacterium that has become an important opportunistic pathogen, largely due to its high degree of natural antibiotic resistance. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, which is controlled in part by OmpC and OmpF porin proteins. OmpF expression is regulated by micF, an RNA transcript encoded upstream of the ompC gene, which hybridizes with the ompF transcript to inhibit its translation. Regulation of S. marcescens porin gene expression, as well as that of micF, was investigated using beta-galactosidase reporter gene fusions in response to 5, 8 and 10% sucrose, 1, 5 and 8 mM salicylate, and different pH and temperature values. beta-Galactosidase activity assays revealed that a lower growth temperature (28 degrees C), a more basic pH (pH 8), and an absence of sucrose and salicylate induce the transcription of the ompF gene, whereas the induction of ompC is stimulated at a higher growth temperature (42 degrees C), acidic pH (pH 6), and maximum concentrations of sucrose (110%) and salicylate (8 mM). In addition, when multiple conditions were tested, temperature had the predominant effect, followed by pH. In this study, it was found that the MicF regulatory mechanism does not play a role in the osmoregulation of the ompF and ompC genes, whereas MicF does repress OmpF expression in the presence of salicylate and high growth temperature, and under low pH conditions.