Hybrid Cyanobacterial-Tobacco Rubisco Supports Autotrophic Growth and Procarboxysomal Aggregation
Hybrid Cyanobacterial-Tobacco Rubisco Supports Autotrophic Growth and Procarboxysomal Aggregation
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杂交蓝藻-烟草 Rubisco 支持自养生长和原羧基体聚集
DOI：
10.1104/pp.19.01193
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发表时间：
2019
期刊：
影响因子：
7.4
通讯作者：
Parry, Martin A. J.
中科院分区：
文献类型：
--
作者：
Orr, Douglas J.;Worrall, Dawn;Lin, Myat T.;Carmo-Silva, Elizabete;Hanson, Maureen R.;Parry, Martin A. J.
许多旨在提高光合作用和作物产量的研究都试图克服主要的二氧化碳固定酶Rubisco的缺点。蓝藻利用二氧化碳浓缩机制（CCM），它封装了Rubisco，特异性较差，但在一个羧酸体微室内具有相对较快的催化速率。蓝藻可以将碳酸氢盐主动转运到细胞内，并将碳酸酐酶定位在具有Rubisco的羧酸体外壳内，通过在高二氧化碳环境中定位，蓝藻能够克服Rubisco的局限性。作为在陆地植物中构建β-蓝藻CCM的持续努力的一部分，我们研究了来自β-蓝藻长聚球菌（Se）的Rubisco大亚基（LSU）在烟草（Nicotiana tabacum）叶绿体中与羧基连接蛋白CcmM35形成聚集Rubisco复合物的潜力。移植物缺乏同源的Se Rubisco小亚基（SSU），表达Se LSU代替烟草LSU，无论是否含有CcmM35。植物能够利用烟草SSU和Se LSU形成杂交酶，允许在高二氧化碳条件下缓慢自养生长。CcmM35能够与Se LSU形成大的Rubisco聚集体，并且这些聚集体含有少量的本地烟草SSU。与野生型烟草和表达Se SSU的烟草相比，缺乏Se SSU的烟草生长迟缓，光合能力差，Rubisco活性显著降低。这些结果表明，在没有同源Se SSU的情况下，Se LSU和CcmM35能够在植物中形成大的聚集体，其中含有激活的Rubisco，使植物生长，尽管速度比表达同源Se SSU的植物慢得多。
Much of the research aimed at improving photosynthesis and crop productivity attempts to overcome shortcomings of the primary CO2-fixing enzyme Rubisco. Cyanobacteria utilize a CO2-concentrating mechanism (CCM), which encapsulates Rubisco with poor specificity but a relatively fast catalytic rate within a carboxysome microcompartment. Alongside the active transport of bicarbonate into the cell and localization of carbonic anhydrase within the carboxysome shell with Rubisco, cyanobacteria are able to overcome the limitations of Rubisco via localization within a high-CO2environment. As part of ongoing efforts to engineer a β-cyanobacterial CCM into land plants, we investigated the potential for Rubisco large subunits (LSU) from the β-cyanobacteriumSynechococcus elongatus(Se) to form aggregated Rubisco complexes with the carboxysome linker protein CcmM35 within tobacco (Nicotiana tabacum) chloroplasts. Transplastomic plants were produced that lacked cognate Se Rubisco small subunits (SSU) and expressed the Se LSU in place of tobacco LSU, with and without CcmM35. Plants were able to form a hybrid enzyme utilizing tobacco SSU and the Se LSU, allowing slow autotrophic growth in high CO2. CcmM35 was able to form large Rubisco aggregates with the Se LSU, and these incorporated small amounts of native tobacco SSU. Plants lacking the Se SSU showed delayed growth, poor photosynthetic capacity, and significantly reduced Rubisco activity compared with both wild-type tobacco and lines expressing the Se SSU. These results demonstrate the ability of the Se LSU and CcmM35 to form large aggregates without the cognate Se SSU in planta, harboring active Rubisco that enables plant growth, albeit at a much slower pace than plants expressing the cognate Se SSU.