Oxygen tension and nutrient starvation are major signals that regulate agfD promoter activity and expression of the multicellular morphotype in Salmonella typhimurium
Oxygen tension and nutrient starvation are major signals that regulate agfD promoter activity and expression of the multicellular morphotype in Salmonella typhimurium
复制标题
DOI：
10.1046/j.1462-2920.2001.00235.x
复制
发表时间：
2001-10-01
影响因子：
5.1
通讯作者：
Römling, U
中科院分区：
文献类型：
--
作者：
Gerstel, U;Römling, U
多细胞行为（rdar形态型）的表达是野生型鼠伤寒沙门氏菌菌株的一个特征。调控rdar形态型表达的关键靶点是agfD启动子。通过对调控型和半组成型agfD启动子的转录融合、蛋白质印迹分析以及rdar形态型的表型分析，研究了不同环境条件对两种rdar形态型（调控型和半组成型，后者与前者的区别在于 -17位之后插入了A）的调控。AgfD启动子的活性强烈依赖于氧张力。在微需氧条件下的丰富培养基以及有氧条件下的基本培养基中观察到表达量最高。调控型rdar形态型仅在启动子活性最高的条件下表达。葡萄糖不影响rdar形态型的表达，并且这两个启动子对pH没有一致的反应。在生长的稳定期，发现氮和磷的耗尽是开启agfD启动子的信号。在生长的对数期，乙醇是增强rdar形态型表达的应激信号。结果表明，尽管调控型和半组成型agfD启动子是多细胞行为表达程度的关键因素，但诸如氧张力、营养物质耗尽和乙醇等常见信号显著改变了它们的表达水平。
Expression of multicellular behaviour (rdar morphotype) is a characteristic of wild-type Salmonella typhimurium strains. The key target for the regulation of rdar morphotype expression is the agfD promoter. The regulation of two rdar morphotypes, regulated and semi-constitutive (the latter differs from the former by the insertion of A after position -17), by various environmental conditions was studied using transcriptional fusions to the regulated and semi-constitutive agfD promoters by Western blot analysis and phenotypic analysis of the rdar morphotype. AgfD promoter activities were strongly dependent on oxygen tension. Expression maxima were observed in rich medium under microaerophilic conditions and in minimal medium under aerobic conditions. The regulated rdar morphotype was only expressed under conditions of maximal promoter activity. Glucose did not influence rdar morphotype expression, and the two promoters showed no consistent response to pH. In the stationary phase of growth, nitrogen and phosphate depletion were found to be signals that switch on the agfD promoters. In the logarithmic phase of growth, ethanol was the stress signal that enhanced rdar morphotype expression. The results indicate that, although the regulated and semi-constitutive agfD promoters are key factors in the grade of expression of the multicellular behaviour, common signals such as oxygen tension, depletion of nutrients and ethanol vary their levels of expression significantly.