Differential roles for menaquinone and demethylmenaquinone in anaerobic electron transport of E. coli and their fnr-independent expression
Differential roles for menaquinone and demethylmenaquinone in anaerobic electron transport of E. coli and their fnr-independent expression
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DOI：
10.1007/bf00422294
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发表时间：
2004
影响因子：
2.8
通讯作者：
G. Unden
中科院分区：
文献类型：
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作者：
G. Unden
大肠杆菌coligrown与葡萄糖在没有添加电子受体的情况下，含有3-4倍以上的萘醌（甲基萘醌加去甲基萘醌）比在O2的存在下。电子受体的存在下，导致在一个轻微的额外增加的萘醌含量。一个fnr基因（编码无氧呼吸的转录激活因子）缺陷的菌株表现出相同的反应。在富马酸盐或二甲亚砜存在的情况下，94%的萘醌由甲基萘醌组成，而在硝酸盐存在的情况下，高达78%的萘醌是去甲基甲基萘醌。以N-氧化三甲胺为受体时，该比例居中。在无氧呼吸的供体底物中，只有甘油对2种醌类化合物含量的比值有显著影响。FNR是fnr基因的基因产物，它不是萘醌合成的厌氧去阻遏所必需的。甲萘醌似乎特别参与富马酸盐或二甲亚砜的呼吸作用，而去甲基甲萘醌则参与硝酸盐的呼吸作用。这两种萘醌似乎都在三甲胺N-氧化物呼吸中起作用。
Escherichia coligrown with glucose in the absence of added electron acceptors contained 3–4 times more naphthoquinones (menaquinone plus demethylmenaquinone) than in the presence of O2. Presence of electron acceptors resulted in a slight additional increase of the naphthoquinone content. A strain defective in thefnrgene, which encodes the transcriptional activator of anaerobic respiration, showed the same response. With fumarate or dimethyl sulfoxide present, 94% of the naphthoquinones consisted of menaquinone, while with nitrate up to 78% was demethylmenaquinone. With trimethylamine N-oxid as the acceptor the proportion was intermediate. From the donor substrates of anaerobic respiration only glycerol had a significant influence on the ratio of the contents of the 2 quinones. It is concluded that FNR, the gene product of thefnrgene, is not required for anaerobic derepression of naphthoquinone viosynthesis. Menaquinone appears to be involved specifically in the respiration with fumarate or dimethyl sulfoxide, and demethylmenaquinone in nitrate respiration. Both naphthoquinones appear to serve in trimethylamine N-oxide respiration.