Li Yujin, Ye Qingqing, He De, Bai Huixian, Wen Jianfan
State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, 650204, China.
Plant Divers. 2019 Sep 26;42(2):120-125. doi: 10.1016/j.pld.2019.09.002. eCollection 2020 Apr.
In photosynthetic eukaryotes, there are two well-characterized fructose-1,6-bisphosphatases (FBPases): the redox-insensitive cytosolic FBPase (cyFBPase), which participates in gluconeogenesis, and the redox-sensitive chloroplastic FBPase (cpFBPase1), which is a critical enzyme in the Calvin cycle. Recent studies have identified a new chloroplastic FBPase, cpFBPase2; however, its phylogenetic distribution, evolutionary origin, and physiological function remain unclear. In this study, we identified and characterized these three FBPase isoforms in diverse, representative photosynthetic lineages and analyzed their phylogeny. In contrast to previous hypotheses, we found that cpFBPase2 is ubiquitous in photosynthetic eukaryotes. Additionally, all cpFBPase2s from diverse lineages form a monophyly, suggesting cpFBPase2 is not a recently evolved enzyme restricted to land plants but rather evolved early in the evolution of photosynthetic organisms, and most likely, in the common ancestor of photosynthetic eukaryotes. cyFBPase was probably first duplicated to produce cpFBPase2, and then the latter duplicated to produce cpFBPase1. The ubiquitous coexistence of these two cpFBPases in chloroplasts is most likely the consequence of adaptation to different redox conditions of photosynthesis, especially those caused by recurrent changes in light conditions.
在光合真核生物中，有两种特征明确的果糖-1,6-二磷酸酶（FBPases）：对氧化还原不敏感的胞质FBPase（cyFBPase），参与糖异生作用；以及对氧化还原敏感的叶绿体FBPase（cpFBPase1），它是卡尔文循环中的关键酶。最近的研究鉴定出一种新的叶绿体FBPase，即cpFBPase2；然而，其系统发育分布、进化起源和生理功能仍不清楚。在本研究中，我们在不同的代表性光合谱系中鉴定并表征了这三种FBPase同工型，并分析了它们的系统发育。与先前的假设相反，我们发现cpFBPase2在光合真核生物中普遍存在。此外，来自不同谱系的所有cpFBPase2形成一个单系群，这表明cpFBPase2不是一种最近进化出来的仅限于陆地植物的酶，而是在光合生物进化的早期，很可能在光合真核生物的共同祖先中就已进化出来。cyFBPase可能首先发生复制产生cpFBPase2，然后后者再复制产生cpFBPase1。这两种cpFBPase在叶绿体中普遍共存很可能是适应光合作用不同氧化还原条件的结果，尤其是由光照条件反复变化引起的那些条件。
