Isolation and Properties of Fumarate Reductase Mutants of Escherichia coli
Isolation and Properties of Fumarate Reductase Mutants of Escherichia coli
复制标题
大肠杆菌富马酸还原酶突变体的分离及性质
DOI：
10.1128/jb.114.2.563-570.1973
复制
发表时间：
1973
影响因子：
3.2
通讯作者：
J. Guest
中科院分区：
文献类型：
--
作者：
M. Spencer;J. Guest
大肠杆菌产生两种相互转化琥珀酸和富马酸的酶：琥珀酸脱氢酶，其适应于三羧酸循环中的氧化作用，和富马酸还原酶，其更有效地催化还原反应，并允许富马酸在厌氧生长中作为电子受体发挥作用。设计了一种甘油加富马酸盐培养基，用于选择缺乏功能性富马酸盐还原酶的突变株（frd），因为它们不能利用富马酸盐作为厌氧电子受体。分离的大多数突变体含有小于1%的亲本富马酸盐还原活性。亲本菌株和frd突变体在有氧和厌氧生长后的延胡索酸还原和琥珀酸氧化活性的测量表明，琥珀酸脱氢酶在厌氧条件下被完全抑制，可测定的琥珀酸氧化活性是由于延胡索酸还原酶可逆地起作用。富马酸还原酶几乎完全抑制在有氧条件下，虽然葡萄糖在一定程度上缓解这种抑制。突变，推测在延胡索酸还原酶的结构基因（frd）中，位于E. coli染色体的接合和转导。frd与ampA位点非常接近，该区域的标记顺序被确定为ampA-frd-purA。
Escherichia coli produces two enzymes which interconvert succinate and fumarate: succinate dehydrogenase, which is adapted to an oxidative role in the tricarboxylic acid cycle, and fumarate reductase, which catalyzes the reductive reaction more effectively and allows fumarate to function as an electron acceptor in anaerobic growth. A glycerol plus fumarate medium was devised for the selection of mutants (frd) lacking a functional fumarate reductase by virtue of their inability to use fumarate as an anaerobic electron acceptor. Most of the mutants isolated contained less than 1% of the parental fumarate reduction activity. Measurements of the fumarate reduction and succinate oxidation activities of parental strains and frd mutants after aerobic and anaerobic growth indicated that succinate dehydrogenase was completely repressed under anaerobic conditions, the assayable succinate oxidation activity being due to fumarate reductase acting reversibly. Fumarate reductase was almost completely repressed under aerobic conditions, although glucose relieved this repression to some extent. The mutations, presumably in the structural gene (frd) for fumarate reductase, were located at approximately 82 min on the E. coli chromosome by conjugation and transduction with phage P1. frd is very close to the ampA locus, and the order of markers in this region was established as ampA-frd-purA.