Theodorou Marina C, Theodorou Evaggelos C, Panagiotidis Christos A, Kyriakidis Dimitrios A
Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece.
Biochim Biophys Acta. 2007 Aug;1770(8):1104-14. doi: 10.1016/j.bbagen.2007.03.009. Epub 2007 Mar 31.
Recent analysis revealed that, in Escherichia coli the AtoS-AtoC/Az two-component system (TCS) and its target atoDAEB operon regulate the biosynthesis of short-chain poly-(R)-3-hydroxybutyrate (cPHB) biosynthesis, a biopolymer with many physiological roles, upon acetoacetate-mediated induction. We report here that spermidine further enhanced this effect, in E. coli that overproduces both components of the AtoS-AtoC/Az TCS, without altering their protein levels. However, bacteria that overproduce either AtoS or AtoC did not display this phenotype. The extrachromosomal introduction of AtoS-AtoC/Az in an E. coli DeltaatoSC strain restored cPHB biosynthesis to the level of the atoSC(+) cells, in the presence of the polyamine. Lack of enhanced cPHB production was observed in cells overproducing the TCS that did not have the atoDAEB operon. Spermidine attained the cPHB enhancement through the AtoC/Az response regulator phosphorylation, since atoC phosphorylation site mutants, which overproduce AtoS, accumulated less amounts of cPHB, compared to their wild-type counterparts. Exogenous addition of N(8)-acetyl-spermidine resulted in elevated amounts of cPHB but at lower levels than those attained upon spermidine addition. Furthermore, AtoS-AtoC/Az altered the intracellular distribution of cPHB according to the inducer recognized by the TCS. Overall, AtoS-AtoC/Az TCS was induced by spermidine to regulate both the biosynthesis and the intracellular distribution of cPHB in E. coli.
最近的分析表明，在大肠杆菌中，AtoS - AtoC/Az双组分系统（TCS）及其靶标atoDAEB操纵子在乙酰乙酸介导的诱导下调节短链聚（R）-3 - 羟基丁酸酯（cPHB）的生物合成，cPHB是一种具有多种生理作用的生物聚合物。我们在此报告，在过量产生AtoS - AtoC/Az TCS两个组分的大肠杆菌中，亚精胺进一步增强了这种效应，且不改变它们的蛋白质水平。然而，过量产生AtoS或AtoC的细菌并未表现出这种表型。在大肠杆菌DeltaatoSC菌株中，在多胺存在的情况下，AtoS - AtoC/Az的染色体外引入将cPHB生物合成恢复到atoSC(+)细胞的水平。在过量产生没有atoDAEB操纵子的TCS的细胞中未观察到cPHB产量的增强。亚精胺通过AtoC/Az反应调节因子的磷酸化实现cPHB的增强，因为过量产生AtoS的atoC磷酸化位点突变体与野生型对应物相比积累的cPHB量更少。外源添加N(8)-乙酰亚精胺导致cPHB量升高，但低于添加亚精胺时达到的水平。此外，AtoS - AtoC/Az根据TCS识别的诱导剂改变cPHB的细胞内分布。总体而言，AtoS - AtoC/Az TCS被亚精胺诱导以调节大肠杆菌中cPHB的生物合成和细胞内分布。
