The function of PROTOPORPHYRINOGEN IX OXIDASE in chlorophyll biosynthesis requires oxidised plastoquinone in Chlamydomonas reinhardtii
The function of PROTOPORPHYRINOGEN IX OXIDASE in chlorophyll biosynthesis requires oxidised plastoquinone in Chlamydomonas reinhardtii
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DOI：
10.1038/s42003-019-0395-5
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发表时间：
2019-05-03
影响因子：
5.9
通讯作者：
Alric, Jean
中科院分区：
文献类型：
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作者：
Brzezowski, Pawel;Ksas, Brigitte;Alric, Jean
在四吡咯生物合成的最后一个常见的酶法步骤中，在导致血红素和叶绿素生物合成的分支点之前，原卟啉原IX(Protogen)被原卟啉原IX氧化酶(PPX)氧化成原卟啉IX(Proto)。在ptox2petB突变体中缺少类囊体定位的叶绿体末端氧化酶2(PTOX2)和细胞色素b6f复合体，导致在光下几乎完全减少了质醌库(PQ库)。在这里，我们表明，缺乏氧化的PQ损害了PPX的功能，导致积累，并随后不受控制地将原蛋白氧化成非代谢的原蛋白。3-(3，4-二氯苯基)-1，1-二甲基脲(DCMU)的加入可防止ptox2PetB中PQ库的过度减少，并减少原生物质的积累。这一观察结果有力地表明，氧化的PQ是莱茵衣藻PPX反应的电子受体。PPX-PQ池相互作用被认为是光合作用电子传递和叶绿素生物合成之间的反馈回路。
In the last common enzymatic step of tetrapyrrole biosynthesis, prior to the branching point leading to the biosynthesis of heme and chlorophyll, protoporphyrinogen IX (Protogen) is oxidised to protoporphyrin IX (Proto) by protoporphyrinogen IX oxidase (PPX). The absence of thylakoid-localised plastid terminal oxidase 2 (PTOX2) and cytochrome b6f complex in the ptox2 petB mutant, results in almost complete reduction of the plastoquinone pool (PQ pool) in light. Here we show that the lack of oxidised PQ impairs PPX function, leading to accumulation and subsequently uncontrolled oxidation of Protogen to non-metabolised Proto. Addition of 3(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) prevents the over-reduction of the PQ pool in ptox2 petB and decreases Proto accumulation. This observation strongly indicates the need of oxidised PQ as the electron acceptor for the PPX reaction in Chlamydomonas reinhardtii. The PPX-PQ pool interaction is proposed to function as a feedback loop between photosynthetic electron transport and chlorophyll biosynthesis.