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정삼일,이명석,김수기,Barry L. Wanner 한국유전학회 2012 Genes & Genomics Vol.34 No.1
Polyphosphate kinase (ppk) synthesizes polyphosphate (polyPn+1) from polyPn and ATP and also catalyses its reversal reaction. In the process of identifying stimuli that affect E. coli ppk transcription, we show that purine limitation activates the E. coli ppk promoter by using a single-copy E. coli ppk promoter-lacZ (ppkPEc-lacZ) fusion and Ez-Tn5 random mutagenesis. The ppkPEc-lacZ expression was greatly induced (seven to eleven fold higher depending on the media) in purF mutant cells (e.g. cvpA::Ez-Tn5 and ΔpurF mutants). This behavior seems to result from the purine starvation because the ppkPEc-lacZ expression in the purF mutant cells was recovered to the level of wild-type cells by the addition of any type of purines (adenine, guanine, adenosine, and guanosine). The ppkPEc-lacZ expression was also increased in other pur mutants but not as much as in the purF mutant cells. Interestingly,the ppkPEc-lacZ expression was not changed in mutants with defective pyrimidine specific genes (e.g. ΔpyrE and ΔthiC). Transcription of four other bacterial ppk promoters also increased in the purF mutant cells. This data imply that purine deficiency seems to be a common and good inducer in bacterial ppk gene expression. Here, we present a novel report about the effect of purine biosynthesis on ppk gene expression in bacteria.
Xueqiao Liu,Gabriela R. Peña Sandoval,Barry L. Wanner,Won Seok Jung,Dimitris Georgellis,권오석 한국미생물학회 2009 The journal of microbiology Vol.47 No.5
The Arc two-component signal transduction system of Escherichia coli comprises the ArcB sensor kinase and the ArcA response regulator. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which, in turn, represses or activates its target operons. ArcA has been shown to be able to autophosphorylate in vitro at the expense of acetyl-P. Here, the in vivo effect of acetyl phosphate on the redox signal transduction by the Arc system was assessed. Our results indicate that acetyl phosphate can modulate the expression of ArcA-P target genes only in the absence of ArcB. Therefore, the acetyl phosphate dependent ArcA phosphorylation route does not seem to play a significant role under physiological conditions.