INVOLVEMENT OF A D-TYPE OXIDASE IN THE NA+-MOTIVE RESPIRATORY-CHAIN OF ESCHERICHIA-COLI GROWING UNDER LOW DELTA(MU)BARH+ CONDITIONS
INVOLVEMENT OF A D-TYPE OXIDASE IN THE NA+-MOTIVE RESPIRATORY-CHAIN OF ESCHERICHIA-COLI GROWING UNDER LOW DELTA(MU)BARH+ CONDITIONS
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DOI：
10.1016/0014-5793(92)80999-w
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发表时间：
1992-07-20
期刊：
影响因子：
3.5
通讯作者：
SKULACHEV, VP
中科院分区：
文献类型：
--
作者：
AVETISYAN, AV;BOGACHEV, AV;SKULACHEV, VP
人们试图找出在低Δ mu（H+）BAR条件下生长的大肠杆菌中，d型或o型两种末端氧化酶中哪一种作为Na+泵。为此目的，已经研究了缺乏d或o氧化酶的突变体。结果表明，d-，o+突变体在低Δ-μ（H+）BAR条件下（使用碱性或含质子载体的生长培养基）生长缓慢或根本不生长。由内而外的亚细胞囊泡从d-，o+突变体不能氧化抗坏血酸和TMPD，不能运输Na+时，琥珀酸被氧化的质子载体的存在下。当NADH被氧化时，发现相同的囊泡转运Na+，就好像Na+-动力性NADH-醌氧化酶是有效的。另一方面，缺乏o氧化酶（d+，o-）的突变体在低Δ mu（H+）BAR条件下生长得与母体E.含有D和O氧化酶的大肠杆菌菌株。相应的囊泡氧化抗坏血酸和TMPD以及琥珀酸，氧化被耦合到质子载体刺激的Na+运输。发现在质子载体存在下的生长诱导母体d+，o+大肠杆菌菌株中d氧化酶水平的强烈增加。结论是d型氧化酶而不是o型氧化酶在大肠杆菌中起Na+泵的作用。在不利于H+循环的条件下生长的大肠杆菌。
An attempt has been made to find out which of the two terminal oxidases, the d-type or the o-type, operates as a Na+ pump in Escherichia coli grown at low DELTA-mu(H+)BAR conditions. For this purpose, mutants lacking either d or o oxidase have been studied. It is shown that a d-,o+ mutant grows slowly or does not grow at all under low DELTA-mu(H+)BAR conditions (alkaline or protonophore-containing growth media were used). Inside-out subcellular vesicles from the d-,o+ mutant cannot oxidize ascorbate and TMPD, and cannot transport Na+ when succinate is oxidized in the presence of a protonophore. The same vesicles are found to transport Na+ when NADH is oxidized as if the Na+-motive NADH-quinone oxidase were operative. On the other hand, a mutant lacking o oxidase (d+,o-) grows at low DELTA-mu(H+)BAR conditions as fast as the maternal E. coli strain containing both d and o oxidases. Corresponding vesicles oxidize ascorbate and TMPD as well as succinate, the oxidations being coupled to the protonophore-stimulated Na+ transport. Growth in the presence of a protonophore is found to induce a strong increase in the d oxidase level in the maternal d+,o+ E coli strain. It is concluded that oxidase of the d-type, rather than of the o-type, operates as a Na+ pump in E. coli grown under conditions unfavorable for the H+ cycle.