ALTERED TRANSCRIPTIONAL PATTERNS AFFECTING SEVERAL METABOLIC PATHWAYS IN STRAINS OF SALMONELLA-TYPHIMURIUM WHICH OVEREXPRESS THE FRUCTOSE REGULON
ALTERED TRANSCRIPTIONAL PATTERNS AFFECTING SEVERAL METABOLIC PATHWAYS IN STRAINS OF SALMONELLA-TYPHIMURIUM WHICH OVEREXPRESS THE FRUCTOSE REGULON
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DOI：
10.1128/jb.171.5.2424-2434.1989
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发表时间：
1989-05-01
影响因子：
3.2
通讯作者：
SAIER, MH
中科院分区：
文献类型：
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作者：
CHIN, AM;FELDHEIM, DA;SAIER, MH
研究了β-半乳糖苷酶与PPS基因(编码磷酸烯醇式丙酮酸[PEP]合成酶)、aceBAK操纵子(分别编码苹果酸合成酶、异柠檬酸裂解酶和异柠檬酸脱氢酶)和PHS操纵子(编码硫代硫酸盐还原酶或控制其表达的调控蛋白)的转录融合表达。在这些菌株中，β-半乳糖苷酶的合成可以通过在葡萄糖存在下的生长或通过存在导致果糖(FEU)调节子结构性表达的FruR突变来抑制。糖异生的五种酶(PEP合成酶、PEP羧基激酶、异柠檬酸裂解酶、苹果酸合成酶和果糖-1，6-二磷酸酶)被葡萄糖或FruR突变抑制，而糖酵解酶、磷酸转移酶系统的酶I和酶II以及磷酸果糖激酶则被葡萄糖或FruR突变所诱导。克隆的fRU调节子基因(不包括FruR)的过表达导致了典型的糖异生、Krebs循环和乙氧基酸分流酶的平行抑制。对鼠伤寒沙门氏菌的温度敏感突变体的研究表明，该蛋白在糖异生底物的利用中起着调节作用。其他突变分析显示，fru基因表达和编码糖异生酶基因的表达之间存在复杂的关系。综上所述，这些结果表明，肠道细菌中编码分解代谢酶、生物合成酶和两性酶的一些基因是转录上的，肠道细菌中编码分解代谢酶、生物合成酶和两性酶的基因在转录上受到复杂的分解代谢抑制/激活机制的调控，这可能涉及磷酸转移酶系统的酶IIIFru作为调节系统的一个组成部分。
Expression of .beta.-galactosidase in transcriptional fusions with the pps gene (encoding phosphoenolpyruvate [PEP] synthase), the aceBAK operon (encoding malate synthase, isocitrate lyase, and isocitrate dehydrogenase kinase, respectively), and the phs operon (encoding either thiosulfate reductase or a regulatory protein controlling its expression) was studied in Salmonella typhimurium. .beta.-Galactosidase synthesis in these strains was repressible either by growth in the presence of glucose or by the presence of a fruR mutation, which resulted in the constitutive expression of the fructose (fru) regulon. Five enzymes of gluconeogenesis (PEP synthase, PEP carboxykinase, isocitrate lyase, malate synthase, and fructose-1,6-diphosphatase) were shown to be repressed either by growth in the presence of glucose or the fruR mutation, while the glycolytic enzymes, enzyme I and enzymes II of the phosphotransferase system as well as phosphofructokinase, were induced either by growth in the presence of glucose or the fruR mutation. Overexpression of the cloned fru regulon genes (not including fruR) resulted in parallel repression of representative gluconeogenic, Krebs cycle, and glyoxylate shunt enzymes. Studies with temperature-sensitive mutants of S. typhimurium which synthesized heat-labile IIIFru proteins provided evidence that this protein plays a role in the regulation of gluconeogenic substrate utilization. Other mutant analyses revealed a complex relationship between fru gene expression and the expression of genes encoding gluconeogenic enzymes. Taken together, the results suggest that a number of genes encoding catabolic, biosynthetic, and amphibolic enzymes in enteric bacteria are transcriptionally genes encoding catabolic, biosynthetic, and amphibolic enzymes in enteric bacteria are transcriptionally regulated by a complex catabolite repression/activation mechanism which may involve enzyme IIIFru of the phosphotransferase system as one component of the regulatory system.