CYTOCHROME-O (CYOABCDE) AND D (CYDAB) OXIDASE GENE-EXPRESSION IN ESCHERICHIA-COLI IS REGULATED BY OXYGEN, PH, AND THE FNR GENE-PRODUCT
CYTOCHROME-O (CYOABCDE) AND D (CYDAB) OXIDASE GENE-EXPRESSION IN ESCHERICHIA-COLI IS REGULATED BY OXYGEN, PH, AND THE FNR GENE-PRODUCT
复制标题
DOI：
10.1128/jb.172.11.6333-6338.1990
复制
发表时间：
1990-11-01
影响因子：
3.2
通讯作者：
GUNSALUS, RP
中科院分区：
文献类型：
--
作者：
COTTER, PA;CHEPURI, V;GUNSALUS, RP
大肠杆菌的有氧呼吸链含有两个末端氧化酶，催化ubiquinol-8的氧化和氧气还原成水。它们是由cyoABCDE编码的细胞色素o氧化酶复合物和由cydAB编码的细胞色素d氧化酶复合物。为了确定这些基因如何响应各种环境刺激（包括氧气）而受到调节，我们通过在野生型和 fnr 突变大肠杆菌菌株中使用 lacZ 蛋白融合体检查了它们的表达。相对于有氧生长，厌氧生长导致 cyoA''-''lacZ 表达抑制 140 倍，并且 cydA''-''lacZ 表达增加 3 倍。两种融合体的厌氧抑制部分由 fnr 基因产物介导，如 fnr 缺失菌株中 cyoA''-''lacZ 表达的 30 倍去抑制和 cydA''-''lacZ 表达的 4 倍去抑制所证明。反式提供野生型 fnr 可恢复对两种融合的野生型抑制。因此，Fnr 充当 cyoABCDE 和 cydAB 表达的厌氧阻遏物。细胞膜的还原-氧化差异谱分析证实了 fnr 基因产物对细胞中细胞色素 d 氧化酶产生的影响。基于观察到的厌氧 cydAB 表达模式，我们提出存在第二种尚未鉴定的调节元件，该元件必须在氧气受到限制时激活 cydAB 表达，或者在有氧情况下抑制 cdyAB 表达。虽然由 cyo-ABCDE 编码的细胞色素 o 氧化酶似乎仅在富氧生长条件下产生，与其生化特性一致，但细胞色素 d 氧化酶在适度需氧条件下表达，并且当氧气受到限制时进一步升高，以便生物体能够更好地应对缺氧条件。我们还检查了 cyoABCDE 和 cydAB 表达对替代碳化合物生长以及培养基 pH 和渗透压变化的响应。
The aerobic respiratory chain of Escherichia coli contains two terminal oxidases that catalyze the oxidation of ubiquinol-8 and the reduction of oxygen to water. They are the cytochrome o oxidase complex encoded by cyoABCDE and the cytochrome d oxidase complex encoded by cydAB. To determine how these genes are regulated in response to a variety of environmental stimuli, including oxygen, we examined their expression by using lacZ protein fusions in wild-type and fnr mutation strains of E. coli. Anaerobic growth resulted in a 140-fold repression of cyoA''-''lacZ expression relative to aerobic growth and a 3-fold increase in cydA''-''lacZ expression. Anaerobic repression of both fusions was mediated in part by the fnr gene product, as evidenced by a 30-fold derepression of cyoA''-''lacZ expression and a 4-fold derepression of cydA''-''lacZ expression in an fnr deletion strain. Supplying wild-type fnr in trans restored wild-type repression for both fusions. Fnr thus functions as an anaerobic repressor of both cyoABCDE and cydAB expression. Reduced-minus-oxidized difference spectrum analyses of cell membranes confirmed the effect of the fnr gene product on the production of cytochrome d oxidase in the cell. Based on the pattern of anaerobic cydAB expression observed, we propose the existence of a second, as yet unidentified, regulatory element that must function either to active cydAB expression as oxygen becomes limiting or to repress cdyAB expression aerobically. Whereas cytochrome o oxidase encoded by cyo-ABCDE appears to be produced only under oxygen-rich growth conditions, in keeping with its biochemical properties, cytochrome d oxidase is expressed moderately aerobically and is elevated yet further when oxygen becomes limiting so that the organism can cope better under oxygen starvation conditions. We also examined cyoABCDE and cydAB expression in response to growth on alternative carbon compounds and to changes in the culture medium pH and osmolarity.