Leang Ching, Krushkal Julia, Ueki Toshiyuki, Puljic Marko, Sun Jun, Juárez Katy, Núñez Cinthia, Reguera Gemma, DiDonato Raymond, Postier Bradley, Adkins Ronald M, Lovley Derek R
Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
BMC Genomics. 2009 Jul 22;10:331. doi: 10.1186/1471-2164-10-331.
The role of the RNA polymerase sigma factor RpoN in regulation of gene expression in Geobacter sulfurreducens was investigated to better understand transcriptional regulatory networks as part of an effort to develop regulatory modules for genome-scale in silico models, which can predict the physiological responses of Geobacter species during groundwater bioremediation or electricity production.
An rpoN deletion mutant could not be obtained under all conditions tested. In order to investigate the regulon of the G. sulfurreducens RpoN, an RpoN over-expression strain was made in which an extra copy of the rpoN gene was under the control of a taclac promoter. Combining both the microarray transcriptome analysis and the computational prediction revealed that the G. sulfurreducens RpoN controls genes involved in a wide range of cellular functions. Most importantly, RpoN controls the expression of the dcuB gene encoding the fumarate/succinate exchanger, which is essential for cell growth with fumarate as the terminal electron acceptor in G. sulfurreducens. RpoN also controls genes, which encode enzymes for both pathways of ammonia assimilation that is predicted to be essential under all growth conditions in G. sulfurreducens. Other genes that were identified as part of the RpoN regulon using either the computational prediction or the microarray transcriptome analysis included genes involved in flagella biosynthesis, pili biosynthesis and genes involved in central metabolism enzymes and cytochromes involved in extracellular electron transfer to Fe(III), which are known to be important for growth in subsurface environment or electricity production in microbial fuel cells. The consensus sequence for the predicted RpoN-regulated promoter elements is TTGGCACGGTTTTTGCT.
The G. sulfurreducens RpoN is an essential sigma factor and a global regulator involved in a complex transcriptional network controlling a variety of cellular processes.
研究了RNA聚合酶σ因子RpoN在嗜硫还原地杆菌基因表达调控中的作用，以更好地理解转录调控网络，这是开发用于基因组规模计算机模型的调控模块的一部分，该模型可预测嗜硫还原地杆菌在地下水生物修复或发电过程中的生理反应。
在所有测试条件下均无法获得rpoN缺失突变体。为了研究嗜硫还原地杆菌RpoN的调控子，构建了一个RpoN过表达菌株，其中rpoN基因的额外拷贝受tac启动子控制。结合微阵列转录组分析和计算预测表明，嗜硫还原地杆菌RpoN控制参与多种细胞功能的基因。最重要的是，RpoN控制编码富马酸/琥珀酸交换体的dcuB基因的表达，这对于嗜硫还原地杆菌以富马酸作为末端电子受体进行细胞生长至关重要。RpoN还控制编码氨同化两条途径中酶的基因，预计这些基因在嗜硫还原地杆菌的所有生长条件下都是必需的。使用计算预测或微阵列转录组分析鉴定为RpoN调控子一部分的其他基因包括参与鞭毛生物合成、菌毛生物合成的基因，以及参与中心代谢酶和细胞色素的基因，这些细胞色素参与向Fe(III)的细胞外电子转移，已知对地下环境中的生长或微生物燃料电池中的发电很重要。预测的RpoN调控启动子元件的共有序列为TTGGCACGGTTTTTGCT。
嗜硫还原地杆菌RpoN是一种必需的σ因子，是参与控制各种细胞过程的复杂转录网络的全局调控因子。
