Regulation of Energy Metabolism by the Extracytoplasmic Function (ECF) σ factors of Arcobacter butzleri

The extracytoplasmic function (ECF) σ factors are fundamental for bacterial adaptation to distinct environments and for survival under different stress conditions. The emerging pathogen Arcobacter butzleri possesses seven putative pairs of σ/anti-σ factors belonging to the ECF family. Here, we report the identification of the genes regulated by five out of the seven A. butzleri ECF σ factors. Three of the ECF σ factors play an apparent role in transport, energy generation and the maintainance of redox balance. Several genes like the nap, sox and tct genes are regulated by more than one ECF σ factor indicating that the A. butzleri ECF σ factors form a network of overlapping regulons. In contrast to other eubacteria, these A. butzleri ECF regulons appear to primarily regulate responses to changing environments in order to meet metabolic needs instead of an obvious role in stress adaptation. Overall design: Eleven condition experiment, wild-type A. butzleri and 10 mutants. Three replicates for isolates RM4810, RM4810∆Aσ1::Km, RM4018Δσ1/Aσ1::Km, RM4810∆Aσ2::Km, RM4018∆σ2/Aσ2::Km, RM4018∆Aσ4::Km, RM4018∆σ4/Aσ4::Km, RM4018∆Aσ5::Km, RM4018∆σ5/Aσ5::Km, RM4018∆Aσ7::Km, and RM4018Δσ7/Aσ7::Km independently grown in BHI and incubated at 30°C on a shaking platform set at 150 rpm. RNA was isolated from 5 ml of mid-logarithmic phase cultures (OD550 of approximately 0.5). A type 2 gene expression experimental design was used, with fluorescently labeled genomic DNA as a reference channel in each experiment as described by Lucchini, S., et al. 2005. Infect Immun 73:88-102.

细胞外功能σ因子（ECF σ因子）对于细菌适应不同环境和在多种压力条件下生存至关重要。新兴病原体弧菌属（Arcobacter butzleri）拥有七对归属ECF家族的假定的σ/反σ因子。在本研究中，我们报告了由A. butzleri七种ECF σ因子中的五种调控的基因的鉴定。其中三种ECF σ因子在物质运输、能量生成和维持氧化还原平衡方面发挥着显著作用。如nap、sox和tct等基因受到多个ECF σ因子的调控，这表明A. butzleri的ECF σ因子构成一个重叠的调控子网络。与其它真细菌相比，这些A. butzleri的ECF调控子似乎主要调节对环境变化的响应，以满足代谢需求，而非在压力适应中发挥明显作用。总体设计：包括11个条件实验，野生型A. butzleri和10种突变体。对于RM4810、RM4810∆Aσ1::Km、RM4018Δσ1/Aσ1::Km、RM4810∆Aσ2::Km、RM4018Δσ2/Aσ2::Km、RM4018∆Aσ4::Km、RM4018Δσ4/Aσ4::Km、RM4018∆Aσ5::Km、RM4018Δσ5/Aσ5::Km、RM4018∆Aσ7::Km和RM4018Δσ7/Aσ7::Km等独立培养于BHI培养基中，并在30°C、150 rpm的摇床中孵育的菌株，每个菌株进行三次重复实验。从对数生长期培养物（OD550约为0.5）中提取5毫升RNA。采用第二型基因表达实验设计，每个实验中以荧光标记的基因组DNA作为参考通道，具体方法参照Lucchini, S.等人于2005年发表的《Infect Immun》杂志第73卷第88-102页的描述。