Fujimoto David F, Higginbotham Robin H, Sterba Kristen M, Maleki Soheila J, Segall Anca M, Smeltzer Mark S, Hurlburt Barry K
Department of Biology, San Diego State University, San Diego, CA 92182, USA.
Mol Microbiol. 2009 Dec;74(6):1445-58. doi: 10.1111/j.1365-2958.2009.06942.x. Epub 2009 Nov 17.
Staphylococcus aureus produces a wide array of virulence factors and causes a correspondingly diverse array of infections. Production of these virulence factors is under the control of a complex network of global regulatory elements, one of which is sarA. sarA encodes a DNA binding protein that is considered to function as a transcription factor capable of acting as either a repressor or an activator. Using competitive ELISA assays, we demonstrate that SarA is present at approximately 50 000 copies per cell, which is not characteristic of classical transcription factors. We also demonstrate that SarA is present at all stages of growth in vitro and is capable of binding DNA with high affinity but that its binding affinity and pattern of shifted complexes in electrophoretic mobility shift assays is responsive to the redox state. We also show that SarA binds to the bacteriophage lambda (lambda) attachment site, attL, producing SarA-DNA complexes similar to intasomes, which consist of bacteriophage lambda integrase, Escherichia coli integration host factor and attL DNA. In addition, SarA stimulates intramolecular excision recombination in the absence of lambda excisionase, a DNA binding accessory protein. Taken together, these data suggest that SarA may function as an architectural accessory protein.
金黄色葡萄球菌产生多种毒力因子，并引发相应的多种感染。这些毒力因子的产生受一个复杂的全局调控元件网络控制，其中之一是sarA。sarA编码一种DNA结合蛋白，该蛋白被认为作为转录因子发挥作用，既能作为阻遏物，也能作为激活物。通过竞争性酶联免疫吸附测定，我们证明每个细胞中SarA约有50000个拷贝，这并非经典转录因子的特征。我们还证明，SarA在体外生长的所有阶段均存在，并且能够以高亲和力结合DNA，但其在电泳迁移率变动分析中的结合亲和力和迁移复合物模式对氧化还原状态有反应。我们还表明，SarA与噬菌体λ附着位点attL结合，产生类似于整合体的SarA-DNA复合物，整合体由噬菌体λ整合酶、大肠杆菌整合宿主因子和attL DNA组成。此外，在没有λ切除酶（一种DNA结合辅助蛋白）的情况下，SarA刺激分子内切除重组。综上所述，这些数据表明SarA可能作为一种结构辅助蛋白发挥作用。
