標題: Oxygen- and growth rate-dependent regulation of Escherichia coli fumarase (FumA, FumB, and FumC) activity
作者: Tseng, CP
Yu, CC
Lin, HH
Chang, CY
Kuo, JT
生物科技學系
Department of Biological Science and Technology
公開日期: 1-Jan-2001
摘要: Escherichia coli contains three biochemically distinct fumarases which catalyze the interconversion of fumarate to L-malate in the tricarboxylic acid cycle, Batch culture studies indicated that fumarase activities varied according to carbon substrate and cell doubling time. Growth rate control of fumarase activities in the wild type and mutants was demonstrated in continuous culture; FumA and FumC activities were induced four- to fivefold when the cell growth rate (k) was lowered from 1.2/h to 0.24/h at 1 and 21% O-2, respectively. There was a twofold induction of FumA and FumC activities when acetate was utilized instead of glucose as the sole carbon source. However, these fumarase activities were still shown to be under growth rate control. Thus, the activity of the fumarases is regulated by the cell growth rate and carbon source utilization independently, Further examination of FumA and FumC activities in a cya mutant suggested that growth rate control of FumA acid FumC activities is cyclic AMP dependent, Although the total fumarase activity increased under aerobic conditions, the individual fumarase activities varied under different oxygen levels. While FumB activity was maximal during anaerobic growth (k = 0.6/h), FumA was the major enzyme under anaerobic cell growth, and the maximum activity was achieved when oxygen was elevated to 1 to 2%. Further increase in the oxygen level caused inactivation of FumA and FumB activities by the high oxidized state, but FumC activity increased simultaneously when the oxygen level aas higher than 4%. The same regulation of the activities of fumarases in response to different oxygen levels was also found in mutants. Therefore, synthesis of the three fumarase enzymes is controlled in a hierarchical fashion depending on the environmental oxygen that the cell encounters.
URI: http://dx.doi.org/10.1128/JB.183.2.461-467.2001
http://hdl.handle.net/11536/29962
ISSN: 0021-9193
DOI: 10.1128/JB.183.2.461-467.2001
期刊: JOURNAL OF BACTERIOLOGY
Volume: 183
Issue: 2
起始頁: 461
結束頁: 467
Appears in Collections:Articles


Files in This Item:

  1. 000166121500006.pdf

If it is a zip file, please download the file and unzip it, then open index.html in a browser to view the full text content.