Functional assembly of the foreign carotenoid lycopene into the photosynthetic apparatus of Rhodobacter sphaeroides, achieved by replacement of the native 3-step phytoene desaturase with its 4-step counterpart from Erwinia herbicola
Functional assembly of the foreign carotenoid lycopene into the photosynthetic apparatus of Rhodobacter sphaeroides, achieved by replacement of the native 3-step phytoene desaturase with its 4-step counterpart from Erwinia herbicola
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DOI：
10.1046/j.1365-2958.2002.02871.x
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发表时间：
2002-04-01
影响因子：
3.6
通讯作者：
Hunter, CN
中科院分区：
文献类型：
--
作者：
Garcia-Asua, G;Cogdell, RJ;Hunter, CN
光合作用生物合成各种各样的类胡萝卜素。这些色素对光合色素-蛋白质复合物的组装、功能和稳定性至关重要，它们被用来熄灭有害的自由基。以光合细菌球形红杆菌（Rhodobacter sphaeroides）为模型系统，探讨类胡萝卜素多样性的起源。用Erwinia除草剂的4步酶取代天然的3步植物烯去饱和酶（CrtI），在Rb中首次实现了螺旋藻黄质途径的显著通量。sphaeroides。Rb。在球形植物中，Erwinia CrtI完成番茄红素的四次去饱和似乎需要缺乏CrtC，并且在CrtC背景下，即使是天然的三步酶也可以合成大量（13%）的番茄红素，除了预期的神经红素。我们认为CrtC羟化酶可以干预植物烯去饱和酶催化的一系列反应。研究了番茄红素合成菌株Rb的特性。sphaeroides。在LH2光收集复合物中，番茄红素以54%的效率将吸收的光能转移到细菌叶绿素中，这比其他含有11个共轭双键的类胡萝卜素的LH2复合物更有利。因此，番茄红素可以加入Rb光合复合物的组装途径。球藻，可以发挥其作为细菌叶绿素的能量供体的作用。
Photosynthetic organisms synthesize a diverse range of carotenoids. These pigments are important for the assembly, function and stability of photosynthetic pigment-protein complexes, and they are used to quench harmful radicals. The photosynthetic bacterium Rhodobacter sphaeroides was used as a model system to explore the origin of carotenoid diversity. Replacing the native 3-step phytoene desaturase (CrtI) with the 4-step enzyme from Erwinia herbicola results in significant flux down the spirilloxanthin pathway for the first time in Rb. sphaeroides . In Rb. sphaeroides , the completion of four desaturations to lycopene by the Erwinia CrtI appears to require the absence of CrtC and, in a crtC background, even the native 3-step enzyme can synthesize a significant amount (13%) of lycopene, in addition to the expected neurosporene. We suggest that the CrtC hydroxylase can intervene in the sequence of reactions catalyzed by phytoene desaturase. We investigated the properties of the lycopene-synthesizing strain of Rb. sphaeroides . In the LH2 light-harvesting complex, lycopene transfers absorbed light energy to the bacteriochlorophylls with an efficiency of 54%, which compares favourably with other LH2 complexes that contain carotenoids with 11 conjugated double bonds. Thus, lycopene can join the assembly pathway for photosynthetic complexes in Rb. sphaeroides , and can perform its role as an energy donor to bacteriochlorophylls.