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Fungal phytochrome chromophore biosynthesis at mitochondria
The EMBO Journal ( IF 11.4 ) Pub Date : 2021-07-13 , DOI: 10.15252/embj.2021108083
Christian Streng 1 , Jana Hartmann 2 , Kai Leister 1 , Norbert Krauß 3 , Tilman Lamparter 3 , Nicole Frankenberg-Dinkel 2 , Franco Weth 4 , Martin Bastmeyer 4 , Zhenzhong Yu 5 , Reinhard Fischer 1
Affiliation  

Mitochondria are essential organelles because of their function in energy conservation. Here, we show an involvement of mitochondria in phytochrome-dependent light sensing in fungi. Phytochrome photoreceptors are found in plants, bacteria, and fungi and contain a linear, heme-derived tetrapyrrole as chromophore. Linearization of heme requires heme oxygenases (HOs) which reside inside chloroplasts in planta. Despite the poor degree of conservation of HOs, we identified two candidates in the fungus Alternaria alternata. Deletion of either one phenocopied phytochrome deletion. The two enzymes had a cooperative effect and physically interacted with phytochrome, suggesting metabolon formation. The metabolon was attached to the surface of mitochondria with a C-terminal anchor (CTA) sequence in HoxA. The CTA was necessary and sufficient for mitochondrial targeting. The affinity of phytochrome apoprotein to HoxA was 57,000-fold higher than the affinity of the holoprotein, suggesting a “kiss-and-go” mechanism for chromophore loading and a function of mitochondria as assembly platforms for functional phytochrome. Hence, two alternative approaches for chromophore biosynthesis and insertion into phytochrome evolved in plants and fungi.

中文翻译:

线粒体中真菌光敏色素发色团的生物合成

线粒体是必不可少的细胞器,因为它们具有能量守恒功能。在这里,我们展示了线粒体参与真菌中光敏色素依赖的光感应。植物色素光感受器存在于植物、细菌和真菌中,含有线性的、血红素衍生的四吡咯作为发色团。血红素的线性化需要存在于植物叶绿体内的血红素加氧酶 (H2O) 。尽管 HOs 的保护程度很差,但我们在真菌Alternaria alternata 中确定了两个候选者. 删除任一表型光敏色素缺失。这两种酶具有协同作用并与光敏色素发生物理相互作用,表明代谢物形成。代谢物通过 HoxA 中的 C 端锚定 (CTA) 序列附着在线粒体表面。CTA 对于线粒体靶向是必要且充分的。光敏色素脱辅基蛋白对 HoxA 的亲和力比全蛋白的亲和力高 57,000 倍,表明发色团加载的“接吻”机制和线粒体作为功能光敏色素的组装平台的功能。因此,在植物和真菌中进化出两种用于生色团生物合成和插入光敏色素的替代方法。
更新日期:2021-09-01
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