Effect of DNA Supercoiling on the Expression of Fumarase Geneses in Escherichia coli

• Main Authors: Yu, Hui-Chun, 尤惠君
• Other Authors: Ching-Ping Tseng
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/16540563305973926112

碩士 === 國立交通大學 === 生物科技研究所 === 85 === Fumarase , one of the tricarboxylic acid cycle enzymes, catalyzes the interconversion of fumarate and L-malate. Three biochemically distinct fumarase have been reported in E.coli. While the fumA and fumB genes encode heat-labile , iron- containing fumarases , the fumC gene product is a heat-stable fumarase which does not reguire iron for its activity. Although three fumarase genes are regulated by Fnr and ArcA proteins , there still has some induction or repression during anaerobic cell growth in fnr and ArcA proteins , there still has some induction or repression during anaerobic cell growth in fnr and arcA double mutant. Hence Fnr and ArcA might not be the only reguirement for the anaerobic regulators of fumarase genes. A topological state of the bacterial chromosome is important for transcription , replication and recombination. To determine how the fumA , fumB and fumC genes are regulated in response to a variety of DNA supercoiling , inhibitors of gyrase and topoisomerase mutation were induced into cells and examined. The results indicated that the effect of supercoiling on expression of three fumarase genes were more conspicious when cells were grown under aerobic conditions. The existance of Fnr and ArcA would affect the effect of varied DNA supercoiling structures on fumA and fumB genes expression , while topA10 mutant caused an increasement of fumC-lacZ expression. Therefore , the change of DNA supercoiling structure will affect the expression of three fumarase genes , and this control is part of mediated by Fnr and ArcA regulators.