PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase.
PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase.
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DOI：
10.1111/mmi.13861
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发表时间：
2017-12
影响因子：
3.6
通讯作者：
Hunter CN
中科院分区：
文献类型：
--
作者：
Chidgey JW;Jackson PJ;Dickman MJ;Hunter CN
兼性光养生物，如球形红杆菌，可以在异养和光合作用生长之间切换。这种转变是由氧分压控制的，涉及细菌叶绿素的大规模生产，细菌叶绿素与血红素共享一条生物合成途径，直到原卟啉IX。在这里，随着Fe2+或Mg2+分别通过铁络合酶或镁络合酶插入到原卟啉中，途径发生了分歧。对这一分支点的严格调控是必不可少的，但人们对呼吸和光合作用生长之间的切换机制知之甚少。我们发现pufQ控制着haem/细菌叶绿素开关；pufQ存在于氧调节的pufQBALMX操纵子中，编码反应中心-捕光光系统复合体。PufQ缺失菌株合成低水平的细菌叶绿素，并积累生物合成前体辅酶AⅢ；该菌株的抑制突变体含有编码铁络合酶的hemH基因突变，显著降低铁络合酶活性，增加细胞细菌叶绿素水平。FLAG免疫沉淀实验回收了一个铁络合酶-PufQ-类胡萝卜素复合体，该复合体被认为是在氧气限制条件下通过引导卟啉流向细菌叶绿素生产来调节血红素/细菌叶绿素分支点。PufQ和光系统基因在同一操纵子中的共同定位确保了四吡咯代谢向细菌叶绿素的转换与反应中心和捕光多肽的产生相协调。
Facultative phototrophs such as Rhodobacter sphaeroides can switch between heterotrophic and photosynthetic growth. This transition is governed by oxygen tension and involves the large‐scale production of bacteriochlorophyll, which shares a biosynthetic pathway with haem up to protoporphyrin IX. Here, the pathways diverge with the insertion of Fe2+ or Mg2+ into protoporphyrin by ferrochelatase or magnesium chelatase, respectively. Tight regulation of this branchpoint is essential, but the mechanisms for switching between respiratory and photosynthetic growth are poorly understood. We show that PufQ governs the haem/bacteriochlorophyll switch; pufQ is found within the oxygen‐regulated pufQBALMX operon encoding the reaction centre–light‐harvesting photosystem complex. A pufQ deletion strain synthesises low levels of bacteriochlorophyll and accumulates the biosynthetic precursor coproporphyrinogen III; a suppressor mutant of this strain harbours a mutation in the hemH gene encoding ferrochelatase, substantially reducing ferrochelatase activity and increasing cellular bacteriochlorophyll levels. FLAG‐immunoprecipitation experiments retrieve a ferrochelatase‐PufQ‐carotenoid complex, proposed to regulate the haem/bacteriochlorophyll branchpoint by directing porphyrin flux toward bacteriochlorophyll production under oxygen‐limiting conditions. The co‐location of pufQ and the photosystem genes in the same operon ensures that switching of tetrapyrrole metabolism toward bacteriochlorophyll is coordinated with the production of reaction centre and light‐harvesting polypeptides.
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影响因子：
4.1
作者：
Cornah, JE;Roper, JM;Smith, AG
通讯作者：
Smith, AG
影响因子：
3.2
作者：
DONOHUE, TJ;HOGER, JH;KAPLAN, S
通讯作者：
KAPLAN, S
影响因子：
2.6
作者：
FORREST, ME;ZUCCONI, AP;BEATTY, JT
通讯作者：
BEATTY, JT
影响因子：
4.3
作者：
Adams, Peter G.;Hunter, C. Neil
通讯作者：
Hunter, C. Neil
影响因子：
2.8
作者：
Fuciman, Marcel;Durchan, Milan;Polivka, Tomas
通讯作者：
Polivka, Tomas