Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS), Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
Computational Biology, Centre for Biotechnology, University Bielefeld, Bielefeld, Germany.
Plant Biol (Stuttg). 2019 Jan;21 Suppl 1:64-76. doi: 10.1111/plb.12904. Epub 2018 Sep 24.
Alanine and aspartate are essential transfer metabolites for C species of the NAD-malic enzyme and phosphoenolpyruvate carboxykinase subtype. To some degree both amino acids are also part of the metabolite shuttle in NADP-malic enzyme plants. In comparison with C species, the majority of C species are therefore characterised by enhanced expression and activity of alanine and aspartate aminotransferases (AT) in the photosynthetically active tissue. Both enzymes exist in multiple copies and have been found in different subcellular compartments. We tested whether different C species show preferential recruitment of enzymes from specific lineages and subcellular compartments. Phylogenetic analysis of alanine and aspartate ATs from a variety of monocot and eudicot C species and their C relatives was combined with subcellular prediction tools and analysis of the subsequent transcript amounts in mature leaves. Recruitment of aspartate AT from a specific subcellular compartment was strongly connected to the biochemical subtype. Deviation from the main model was however observed in Gynandropsis gynandra. The configuration of alanine AT generally differed in monocot and eudicot species. C monocots recruited an alanine AT from a specific cytosolic branch, but eudicots use alanine AT copies from a mitochondrial branch. Generally, plants display high plasticity in the setup of the C pathway. Beside the common models for the different C subtypes, individual solutions were found for plant groups or lineages.
丙氨酸和天冬氨酸是 NAD-苹果酸酶和磷酸烯醇丙酮酸羧激酶 C 亚型的必需转移代谢物。在某种程度上，这两种氨基酸也是 NADP-苹果酸酶植物中代谢物穿梭的一部分。与 C 型相比，大多数 C 型在光合作用组织中表现出增强的丙氨酸和天冬氨酸转氨酶（AT）的表达和活性。这两种酶都存在多个副本，并在不同的亚细胞隔室中发现。我们测试了不同的 C 型是否优先从特定谱系和亚细胞隔室招募酶。对来自各种单子叶植物和双子叶植物 C 种及其 C 相关物的丙氨酸和天冬氨酸 AT 的系统发育分析，结合亚细胞预测工具和成熟叶片中随后的转录物丰度分析。天冬氨酸 AT 从特定亚细胞隔室的招募与生物化学亚型强烈相关。然而，在 Gynandropsis gynandra 中观察到偏离主要模型的情况。丙氨酸 AT 的配置在单子叶植物和双子叶植物中通常不同。C 单子叶植物从特定的细胞质分支招募丙氨酸 AT，但双子叶植物使用来自线粒体分支的丙氨酸 AT 副本。一般来说，植物在 C 途径的设置中表现出很高的灵活性。除了不同 C 亚型的常见模型外，还为植物群或谱系找到了个别解决方案。
