Tetrapyrrole signal as a cell-cycle coordinator from organelle to nuclear DNA replication in plant cells
Tetrapyrrole signal as a cell-cycle coordinator from organelle to nuclear DNA replication in plant cells
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DOI：
10.1073/pnas.0804270105
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发表时间：
2009-01-20
影响因子：
11.1
通讯作者：
Tanaka, Kan
中科院分区：
文献类型：
--
作者：
Kobayashi, Yuki;Kanesaki, Yu;Tanaka, Kan
真核细胞起源于古老的原核生物的内共生关系，植物细胞拥有3个基因组作为这种进化的残余。在植物细胞中，质体和线粒体DNA复制[细胞器DNA复制（ODR）]发生在随后由细胞核DNA复制（NDR）和细胞分裂组成的细胞周期之前。然而，这些具有不同起源的基因组的复制协调机制在很大程度上是未知的。在这里，我们发现NDR是由植物细胞中的四吡咯信号调节的，该信号被认为是细胞器到细胞核的逆行信号。在同步培养的原始红藻中，a型细胞周期蛋白依赖性激酶（CDKA）的特异性抑制可以阻止NDR，但不能阻止细胞周期开始后的ODR。相反，萘啶酸对ODR的抑制也导致NDR的抑制，说明NDR对ODR有严格的依赖性。通过添加四吡啶中间体原卟啉IX （ProtoIX）或Mg-ProtoIX，绕过了NDR对ODR的要求，这两种中间体都能激活CDKA而不诱导ODR。在培养的烟草细胞（by -2）中也观察到这一机制，钠啶酸对ODR的抑制阻止了CDKA的激活和NDR， Mg-ProtoIX可以绕过这些抑制而不诱导ODR。因此，我们表明四吡咯介导的细胞器-细胞核复制耦合是植物细胞中一个进化保守的过程。
Eukaryotic cells arose from an ancient endosymbiotic association of prokaryotes, with plant cells harboring 3 genomes as the remnants of such evolution. In plant cells, plastid and mitochondrial DNA replication [organelle DNA replication (ODR)] occurs in advance of the subsequent cell cycles composed of nuclear DNA replication (NDR) and cell division. However, the mechanism by which replication of these genomes with different origins is coordinated is largely unknown. Here, we show that NDR is regulated by a tetrapyrrole signal in plant cells, which has been suggested as an organelle-to-nucleus retrograde signal. In synchronized cultures of the primitive red alga Cyanidioschyzon merolae, specific inhibition of A-type cyclin-dependent kinase (CDKA) prevented NDR but not ODR after onset of the cell cycle. In contrast, inhibition of ODR by nalidixic acid also resulted in inhibition of NDR, indicating a strict dependence of NDR on ODR. The requirement of ODR for NDR was bypassed by addition of the tetrapyrrole intermediates protoporphyrin IX (ProtoIX) or Mg-ProtoIX, both of which activated CDKA without inducing ODR. This scheme was also observed in cultured tobacco cells (BY-2), where inhibition of ODR by nalidixic acid prevented CDKA activation and NDR, and these inhibitions were circumvented by Mg-ProtoIX without inducing ODR. We thus show that tetrapyrrole-mediated organelle-nucleus replicational coupling is an evolutionary conserved process among plant cells.