An isoleucine residue acts as a thermal and regulatory switch in wheat Rubisco activase
An isoleucine residue acts as a thermal and regulatory switch in wheat Rubisco activase
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DOI：
10.1111/tpj.14766
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发表时间：
2020-05-04
期刊：
影响因子：
7.2
通讯作者：
Carmo-Silva, Elizabete
中科院分区：
文献类型：
--
作者：
Degen, Gustaf E.;Worrall, Dawn;Carmo-Silva, Elizabete
Rubisco是生物圈中碳固定的守门人，其分子伴侣Rubisco激活酶(RCA)对其的调节对光合作用和植物生长至关重要。利用ATP水解产生的能量，RCA促进抑制剂的释放，并将催化活性恢复到Rubisco活性部位。然而，RCA对适度的热胁迫很敏感，并且随着温度的升高而逐渐受到抑制，超过了光合作用的最适温度。在这里，我们确定了一个单一的氨基酸替换(M159I)，它从根本上改变了面包小麦(Triticum aestivum L.)中RCA的温度和调节特性。利用定点突变，我们证明了M159I替代在体外将最丰富的RCA亚型的最适温度延长了5℃，同时保持了RCA激活Rubisco的效率。结果表明，这种单一氨基酸的替代在小麦RCA中起着温度和调节开关的作用，随着气温变暖和变得更加不稳定，可以利用这种开关来提高这种谷类作物的气候适应能力和碳同化效率。
The regulation of Rubisco, the gatekeeper of carbon fixation into the biosphere, by its molecular chaperone Rubisco activase (Rca) is essential for photosynthesis and plant growth. Using energy from ATP hydrolysis, Rca promotes the release of inhibitors and restores catalytic competence to Rubisco-active sites. Rca is sensitive to moderate heat stress, however, and becomes progressively inhibited as the temperature increases above the optimum for photosynthesis. Here, we identify a single amino acid substitution (M159I) that fundamentally alters the thermal and regulatory properties of Rca in bread wheat (Triticum aestivum L.). Using site-directed mutagenesis, we demonstrate that the M159I substitution extends the temperature optimum of the most abundant Rca isoform by 5 degrees C in vitro, while maintaining the efficiency of Rubisco activation by Rca. The results suggest that this single amino acid substitution acts as a thermal and regulatory switch in wheat Rca that can be exploited to improve the climate resilience and efficiency of carbon assimilation of this cereal crop as temperatures become warmer and more volatile.