Atkinson Nicky, Leitão Nuno, Orr Douglas J, Meyer Moritz T, Carmo-Silva Elizabete, Griffiths Howard, Smith Alison M, McCormick Alistair J
SynthSys & Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK.
Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
New Phytol. 2017 Apr;214(2):655-667. doi: 10.1111/nph.14414. Epub 2017 Jan 13.
Introducing components of algal carbon concentrating mechanisms (CCMs) into higher plant chloroplasts could increase photosynthetic productivity. A key component is the Rubisco-containing pyrenoid that is needed to minimise CO retro-diffusion for CCM operating efficiency. Rubisco in Arabidopsis was re-engineered to incorporate sequence elements that are thought to be essential for recruitment of Rubisco to the pyrenoid, namely the algal Rubisco small subunit (SSU, encoded by rbcS) or only the surface-exposed algal SSU α-helices. Leaves of Arabidopsis rbcs mutants expressing 'pyrenoid-competent' chimeric Arabidopsis SSUs containing the SSU α-helices from Chlamydomonas reinhardtii can form hybrid Rubisco complexes with catalytic properties similar to those of native Rubisco, suggesting that the α-helices are catalytically neutral. The growth and photosynthetic performance of complemented Arabidopsis rbcs mutants producing near wild-type levels of the hybrid Rubisco were similar to those of wild-type controls. Arabidopsis rbcs mutants expressing a Chlamydomonas SSU differed from wild-type plants with respect to Rubisco catalysis, photosynthesis and growth. This confirms a role for the SSU in influencing Rubisco catalytic properties.
将藻类碳浓缩机制（CCM）的组件引入高等植物叶绿体中可以提高光合生产力。一个关键组件是含核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）的蛋白核，它对于将二氧化碳反向扩散降至最低以实现CCM的运行效率是必需的。对拟南芥中的Rubisco进行了重新设计，使其包含被认为是将Rubisco招募到蛋白核所必需的序列元件，即藻类Rubisco小亚基（SSU，由rbcS编码）或仅表面暴露的藻类SSUα螺旋。表达含有莱茵衣藻SSUα螺旋的“具有蛋白核能力”的嵌合拟南芥SSU的拟南芥rbcS突变体叶片可以形成具有与天然Rubisco相似催化特性的杂交Rubisco复合物，这表明α螺旋在催化方面是中性的。产生接近野生型水平杂交Rubisco的互补拟南芥rbcS突变体的生长和光合性能与野生型对照相似。表达衣藻SSU的拟南芥rbcS突变体在Rubisco催化、光合作用和生长方面与野生型植物不同。这证实了SSU在影响Rubisco催化特性方面的作用。
