Lee Chun Pong, Eubel Holger, O'Toole Nicholas, Millar A Harvey
Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
Mol Cell Proteomics. 2008 Jul;7(7):1297-316. doi: 10.1074/mcp.M700535-MCP200. Epub 2008 Apr 1.
Heterogeneity of the mitochondrial proteome in plants underlies fundamental differences in the roles of these organelles in different tissues. We quantitatively compared the mitochondrial proteome isolated from a non-photosynthetic cell culture model with more specialized mitochondria isolated from photosynthetic shoots. Differences in intact mitochondrial respiratory rates with various substrates and activities of specific enzymes provided a backdrop of the functional variation between these mitochondrial populations. Proteomics comparisons provided a deep insight into the different steady-state abundances of specific mitochondrial proteins. Combined these data showed the elevated level of the photorespiratory apparatus and its complex interplay with glycolate, cysteine, formate, and one-carbon metabolism as well as the decrease of selected parts of the tricarboxylic acid cycle, alterations in amino acid metabolism focused on 2-oxoglutarate generation, and degradation of branched chain amino acids. Comparisons with microarray analysis of these tissue types showed a positive, mild correlation between mRNA and mitochondrial protein abundance, a tighter correlation for specific biochemical pathways, but over 78% concordance in direction between changes in protein and transcript abundance in the two tissues. Overall these results indicated that the majority of the variation in the plant mitochondrial proteome occurred in the matrix, highlighted the constitutive nature of the respiratory apparatus, and showed the differences in substrate choice and/or availability during photosynthetic and non-photosynthetic metabolism.
植物线粒体蛋白质组的异质性是这些细胞器在不同组织中发挥作用存在根本差异的基础。我们定量比较了从非光合细胞培养模型中分离出的线粒体蛋白质组与从光合茎中分离出的更具特异性的线粒体。完整线粒体对各种底物的呼吸速率以及特定酶的活性差异为这些线粒体群体之间的功能差异提供了背景。蛋白质组学比较深入洞察了特定线粒体蛋白质不同的稳态丰度。综合这些数据表明，光呼吸装置水平升高，且其与乙醇酸、半胱氨酸、甲酸和一碳代谢存在复杂的相互作用，同时三羧酸循环的某些部分减少，氨基酸代谢变化集中在2-酮戊二酸的生成以及支链氨基酸的降解。与这些组织类型的微阵列分析比较显示，mRNA与线粒体蛋白质丰度之间存在正的、轻度的相关性，特定生化途径的相关性更紧密，但两种组织中蛋白质和转录本丰度变化方向的一致性超过78%。总体而言，这些结果表明植物线粒体蛋白质组的大部分变异发生在线粒体基质中，突出了呼吸装置的组成性质，并显示了光合和非光合代谢过程中底物选择和/或可用性的差异。
