Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli.
Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli.
复制标题
细胞生长速率对大肠杆菌厌氧呼吸途径操纵子frdABCD、dmsABC和narGHJI表达的影响。
DOI：
10.1128/jb.176.21.6599-6605.1994
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发表时间：
1994
影响因子：
3.2
通讯作者：
Gunsalus,RP
中科院分区：
文献类型：
--
作者：
Tseng,CP;Hansen,AK;Cotter,P;Gunsalus,RP
大肠杆菌中的富马酸还原酶 (frdABCD)、二甲基亚砜 (DMSO)-三甲胺-N-氧化物 (TMAO) 还原酶 (dmsABC) 和硝酸还原酶 (narGHJI) 操纵子分别编码参与电子受体富马酸、DMSO 或 TMAO 和硝酸盐无氧呼吸的酶。它们根据厌氧和硝酸盐的可用性进行调节。为了确定每个操纵子如何响应细胞生长速率和氧气利用率的变化而受到调节，在连续培养过程中检查了frdA-lacZ、dmsA-lacZ和narG-lacZ融合基因的表达。细胞生长速率发生变化后，每个厌氧电子传递途径操纵子融合的反应有所不同。尽管在有氧生长期间，随着生长速率从 0.60/小时降至 0.12/小时，frdA-lacZ 表达增加了五倍，但在厌氧条件下几乎没有变化。相反，narG-lacZ 表达的生长速率依赖性表达发生在厌氧条件下，但不在有氧条件下。最后，dmsA-lacZ 表达对于任何测试的生长速率都没有很大变化。当细胞从需氧生长条件转变为厌氧生长条件时，每种融合物的表达以中等速率增加，并在达到新的平衡值之前达到峰值或“过冲”。这种“超调”现象与 fnr 基因产物无关，fnr 基因产物在厌氧条件下充当每个呼吸操纵子的转录激活剂。与 narG-lacZ 表达的中等厌氧诱导率相反，添加硝酸盐引起快速诱导反应。细胞似乎有很多方法来调整细胞呼吸以响应细胞生长条件的变化。
The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine-N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHJI) operons in Escherichia coli encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO or TMAO, and nitrate, respectively. They are regulated in response to anaerobiosis and nitrate availability. To determine how each operon is regulated in response to changes in cell growth rate and in oxygen availability, expression of frdA-lacZ, dmsA-lacZ, and narG-lacZ fusion genes was examined during continuous culture. After a change in the cell growth rate, each anaerobic electron transport pathway operon fusion responded somewhat differently. Whereas frdA-lacZ expression increased by fivefold as the growth rate decreased from 0.60 to 0.12/hour during aerobic growth, little change was seen under anaerobic conditions. In contrast, growth rate-dependent expression of narG-lacZ expression occurred under anaerobic conditions but not under aerobic conditions. Finally, dmsA-lacZ expression did not vary greatly for any of the growth rates tested. When cells were shifted from aerobic to anaerobic growth conditions, expression of each fusion increased at a moderate rate and peaked or "overshot" before reaching a new equilibrium value. This "overshoot" phenomenon was independent of the fnr gene product, which functions as a transcriptional activator of each respiratory operon during anaerobic conditions. In contrast to the moderate rate of anaerobic induction seen for narG-lacZ expression, the addition of nitrate caused a rapid induction response. The cell appears to have many ways to adjust cell respiration in response to changes in cell growth conditions.