Identification of a novel gene for biosynthesis of a bacteroid-specific electron carrier menaquinone.
Identification of a novel gene for biosynthesis of a bacteroid-specific electron carrier menaquinone.
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类杆菌特异性电子载体甲萘醌生物合成新基因的鉴定
DOI：
10.1371/journal.pone.0028995
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Li Y
中科院分区：
文献类型：
--
作者：
Xie F;Cheng G;Xu H;Wang Z;Lei L;Li Y
泛醌（UQ）被认为是根瘤菌在自由生活和共生条件下产生ATP的电子传递的电子介质。当突变时，dmtH基因在紫云英上具有形成无效根瘤的共生表型。该基因是从华癸中慢生根瘤菌7653 R转座子插入突变体文库中分离得到的。DNA序列和蛋白质保守结构域分析表明，dmtH编码去甲基甲萘醌（DMK）甲基转移酶，催化甲基萘醌（MK）生物合成的最后一步。比较分析表明，dmtH同源物存在于只有少数根瘤菌。实时荧光定量PCR结果显示dmtH基因为类杆菌特异性基因。7653 R在接种后25天表达量最高。基因破坏和互补试验表明，dmtH基因是必需的类菌体发育和共生固氮能力。从野生型菌株7653 R和突变菌株HK 116中提取MK和UQ。微氧条件下MK-7和好氧条件下UQ-10在M.华癸7653 R.通过体外甲基转移酶活性的测定证实了DmtH蛋白的预测功能。这些结果表明，MK-7代替UQ在M中用作电子载体。华癸7653 R类细菌。
Ubiquinone (UQ) has been considered as an electron mediator in electron transfer that generates ATP in Rhizobium under both free-living and symbiosis conditions. When mutated, the dmtH gene has a symbiotic phenotype of forming ineffective nodules on Astragalus sinicus. The gene was isolated from a Mesorhizobium huakuii 7653R transposon-inserted mutant library. The DNA sequence and conserved protein domain analyses revealed that dmtH encodes demethylmenaquinone (DMK) methyltransferase, which catalyzes the terminal step of menaquinone (MK) biosynthesis. Comparative analysis indicated that dmtH homologs were present in only a few Rhizobia. Real-time quantitative PCR showed dmtH is a bacteroid-specific gene. The highest expression was seen at 25 days after inoculation of strain 7653R. Gene disruption and complementation tests demonstrated that the dmtH gene was essential for bacteroid development and symbiotic nitrogen fixation ability. MK and UQ were extracted from the wild type strain 7653R and mutant strain HK116. MK-7 was accumulated under microaerobic condition and UQ-10 was accumulated under aerobic condition in M. huakuii 7653R. The predicted function of DmtH protein was confirmed by the measurement of methyltransferase activity in vitro. These results revealed that MK-7 was used as an electron carrier instead of UQ in M. huakuii 7653R bacteroids.
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影响因子：
3.2
作者：
Preisig, O;Zufferey, R;Hennecke, H
通讯作者：
Hennecke, H
影响因子：
4.8
作者：
KoikeTakeshita, A;Koyama, T;Ogura, K
通讯作者：
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影响因子：
3.6
作者：
Brondijk, THC;Fiegen, D;Cole, JA
通讯作者：
Cole, JA
影响因子：
3.2
作者：
Bekker, Martijn;Alexeeva, Svetlana;Hellingwerf, Klaas
通讯作者：
Hellingwerf, Klaas
影响因子：
3.2
作者：
Murphy, Julie N.;Saltikov, Chad W.
通讯作者：
Saltikov, Chad W.