Role of purine biosynthetic intermediates in response to folate stress in Escherichia coli.
Role of purine biosynthetic intermediates in response to folate stress in Escherichia coli.
复制标题
嘌呤生物合成中间体在大肠杆菌中响应叶酸应激的作用。
DOI：
10.1128/jb.172.12.7200-7210.1990
复制
发表时间：
1990
影响因子：
3.2
通讯作者：
Matthews,RG
中科院分区：
文献类型：
--
作者：
Rohlman,CE;Matthews,RG
叶酸在合成代谢中起着核心作用，它为核苷酸和氨基酸的生物合成提供不同程度氧化的单碳单位。5-氨基-4-咪唑甲酰胺核苷5‘-三磷酸(ZTP)是嘌呤生物合成的中间体，在鼠伤寒沙门氏菌中被认为是细胞叶酸胁迫的信号，并介导了对叶酸胁迫的生理应答(B.R.Bochner和B.N.Ames，Cell 29：929-937,1982)。我们研究了大肠杆菌对药物Picofuranine、甲氧嘧啶和磺胺噻唑钠或对氨基苯甲酸(PABA)饥饿诱导的叶酸胁迫的生理反应。对核苷酸池的分析表明，与Bochner和Ames以前在鼠伤寒沙门氏菌中观察到的那样，原养菌株的Picofuranine或甲氧普林处理或限制PABA的PABA营养缺陷菌的生长诱导了核苷酸ZTP的产生。通过测定处理细胞提取物的叶酸/蛋白质比，发现ZTP及其前体5-氨基-4-咪唑甲酰胺核苷5‘-单磷酸(ZMP)在大肠杆菌中的积累与叶酸胁迫没有很好的相关性。用Picofuranine处理细胞后，细胞提取液中5-氨基-4-咪唑甲酰胺核糖核苷酸(Z-核糖核苷酸)显着积累，但叶酸/蛋白质比下降不明显。在药物浓度下，磺胺噻唑钠使处理细胞的生长速度和叶酸/蛋白质比下降三倍，导致Z-核糖核苷酸在大肠杆菌中几乎没有积累。在该菌株中，组氨酸抑制ZMP和ZTP的合成。用甲氧嘧啶处理该菌株的细胞后，细胞提取物的叶酸/蛋白质比降低，但阻断Z-核苷酸积累并不影响处理细胞的叶酸耗竭程度，对该菌株对甲氧嘧啶生长抑制的抵抗力影响很小。用双向凝胶电泳法分析了甲氧苄氨嘧啶或多西呋喃对该菌株诱导的蛋白质表达模式。在含有或不含组氨酸的培养液中进行处理时，蛋白质表达没有差异。这些研究未能在大肠杆菌中提供由ZTP控制的叶酸胁迫调节的证据。
Folic acid plays a central role in anabolic metabolism by supplying single-carbon units at varied levels of oxidation for both nucleotide and amino acid biosyntheses. It has been proposed that 5-amino-4-imidazole carboxamide riboside 5'-triphosphate (ZTP), an intermediate in de novo purine biosynthesis, serves as a signal of cellular folate stress and mediates a physiologically beneficial response to folate stress in Salmonella typhimurium (B. R. Bochner, and B. N. Ames, Cell 29:929-937, 1982). We examined the physiological response of Escherichia coli to folate stress induced by the drugs psicofuranine, trimethoprim, and sodium sulfathiazole or by p-aminobenzoic acid (pABA) starvation. Analysis of nucleotide pools showed that psicofuranine or trimethoprim treatment of a prototrophic strain or growth of a pABA auxotroph on limiting pABA induced the production of the nucleotide ZTP, as previously observed in S. typhimurium by Bochner and Ames. Accumulation of ZTP and its precursor 5-amino-4-imidazole carboxamide riboside 5'-monophosphate (ZMP) did not correlate well with folate stress in E. coli, as measured by determination of the folate/protein ratios of extracts of treated cells. Treatment of cells with psicofuranine caused a marked accumulation of 5-amino-4-imidazole carboxamide ribonucleotides (Z-ribonucleotides) but a statistically insignificant drop in the folate/protein ratio of cell extracts. Sodium sulfathiazole treatment at a drug concentration that led to a threefold drop in the growth rate and in the folate/protein ratio of treated cells led to little accumulation of Z-ribonucleotides in E. coli A purF his+ strain which produces ZTP and ZMP when treated with trimethoprim was constructed. In this strain, histidine represses the synthesis of both ZMP and ZTP. Treatment of cells of this strain with trimethoprim resulted in a decrease in the folate/protein ratio of cell extracts, but a blockade of Z-ribonucleotide accumulation did not affect the extent of folate depletion seen in treated cells and had only a small effect on the resistance of this strain to growth inhibition by trimethoprim. The patterns of protein expression induced by treatment of this strain with trimethoprim or psicofuranine were examined by two-dimensional electrophoretic resolution of the total cellular proteins. No differences in protein expression were seen when the treatment were performed in media containing or lacking histidine. These studies failed to provide evidence in E. coli for a folate stress regulon controlled by ZTP.