DNA supercoiling, ATP generation and cell division gene expression are regulated by carbon source and growth rate in Escherichia coli

• Main Authors: Hui-Wen Cheng, 鄭惠文
• Other Authors: Ching-Ping Tseng
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/pvrvhv

碩士 === 國立交通大學 === 生物科技系所 === 92 === To understand the expression of ATP generation and cell division genes in different carbon sources, we individually used acetate, glucose, glycerol or succinate as a sole carbon for energy source. The results of this study showed that the expression of ATP generating genes in metabolic pathway varied with carbon sources and ATP concentration increased with cell growth rate. Comparision with the wild-type strain and relA spoT double mutant, the growth rate and ATP yields were changed, but ATP/ADP ratio remained at the same level. DNA supercoiling was dependent on ATP/ADP ratio. Whereas ppGpp did not change DNA supercoiling. Under various growth conditions, fast-growing E. coli cells were larger than slowly growing ones. Starvation of the cells resulted in filamentous morphology. In addition, the results clearly showed that relA spoT double mutant had more filamentous than wild-type cells regardless acetate or glucose as carbon substrates. It was also notable that the filamentous features provided the phenotypic clues for ppGpp function. However, the morphology raised the possibility of indirect, rather than direct, effects of ppGpp. It indicated that a link between the levels of ppGpp and cell division, which ppGpp could act as a positive regulator of the expression of ftsZ gene. Deficiency of ppGpp (relA spoT double mutant) drastically reduced the expression of minC and minD. These results also suggested that ppGpp was important factor involved in the regulation of cell cycle of E. coli under starvation condition.