Rigas Stamatis, Daras Gerasimos, Tsitsekian Dikran, Alatzas Anastasios, Hatzopoulos Polydefkis
Department of Biotechnology, Agricultural University of Athens Athens, Greece.
Front Plant Sci. 2014 Apr 11;5:145. doi: 10.3389/fpls.2014.00145. eCollection 2014.
Lon is the first identified ATP-dependent protease highly conserved across all kingdoms. Model plant species Arabidopsis thaliana has a small Lon gene family of four members. Although these genes share common structural features, they have distinct properties in terms of gene expression profile, subcellular targeting and substrate recognition motifs. This supports the notion that their functions under different environmental conditions are not necessarily redundant. This article intends to unravel the biological role of Lon proteases in energy metabolism and plant growth through an evolutionary perspective. Given that plants are sessile organisms exposed to diverse environmental conditions and plant organelles are semi-autonomous, it is tempting to suggest that Lon genes in Arabidopsis are paralogs. Adaptive evolution through repetitive gene duplication events of a single archaic gene led to Lon genes with complementing sets of subfunctions providing to the organism rapid adaptability for canonical development under different environmental conditions. Lon1 function is adequately characterized being involved in mitochondrial biogenesis, modulating carbon metabolism, oxidative phosphorylation and energy supply, all prerequisites for seed germination and seedling establishment. Lon is not a stand-alone proteolytic machine in plant organelles. Lon in association with other nuclear-encoded ATP-dependent proteases builds up an elegant nevertheless, tight interconnected circuit. This circuitry channels properly and accurately, proteostasis and protein quality control among the distinct subcellular compartments namely mitochondria, chloroplasts, and peroxisomes.
Lon是首个被鉴定出的在所有生物界中高度保守的ATP依赖性蛋白酶。模式植物拟南芥拥有一个由四个成员组成的小型Lon基因家族。尽管这些基因具有共同的结构特征，但在基因表达谱、亚细胞定位和底物识别基序方面却具有不同的特性。这支持了这样一种观点，即它们在不同环境条件下的功能不一定是冗余的。本文旨在从进化的角度揭示Lon蛋白酶在能量代谢和植物生长中的生物学作用。鉴于植物是固着生物，暴露于各种环境条件下，且植物细胞器是半自主的，因此很容易认为拟南芥中的Lon基因是旁系同源基因。通过单个古老基因的重复基因复制事件进行的适应性进化，产生了具有互补亚功能集的Lon基因，为生物体在不同环境条件下的正常发育提供了快速适应性。Lon1的功能已得到充分表征，它参与线粒体生物发生、调节碳代谢、氧化磷酸化和能量供应，这些都是种子萌发和幼苗建立的先决条件。Lon在植物细胞器中不是一个独立的蛋白水解机器。Lon与其他核编码的ATP依赖性蛋白酶结合，构建了一个优雅但紧密相连的回路。这个回路在不同的亚细胞区室，即线粒体、叶绿体和过氧化物酶体之间，正确而精确地引导蛋白质稳态和蛋白质质量控制。
