The chloroplast division protein FtsZ is encoded by a nucleomorph gene in cryptomonads
The chloroplast division protein FtsZ is encoded by a nucleomorph gene in cryptomonads
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DOI：
10.1007/s004380050887
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发表时间：
1998-11-01
期刊：
影响因子：
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通讯作者：
Maier, UG
中科院分区：
文献类型：
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作者：
Fraunholz, MJ;Moerschel, E;Maier, UG
吉拉德藻（Guillardia theta）是一种隐藻，其光合共生体是通过二次内共生获得的。核形（nucleomorph），即真核内共生体的残留细胞核，含有三条线性染色体，总编码能力为515kb。对核形基因组的测序表明，它编码一个与细菌细胞分裂蛋白FtsZ同源的开放阅读框（ORF），这支持了FtsZ在叶绿体中普遍存在的假说。我们发现核形编码的ftsZ基因被转录。转录本是多聚腺苷酸化的，因此显示出真核转录本的典型特征。然而，核形mRNA的3'加工不准确。吉拉德藻中核形基因的转录本与相邻的非翻译区（UTR）和编码区重叠。我们证明编码NmFtsZ的阅读框没有被内含子中断。该蛋白质的亚细胞定位显示FtsZ仅定位在吉拉德藻的叶绿体中，这表明FtsZ被输入到细胞器中。
Guillardia theta is a cryptomonad alga, whose phototrophic symbiont was acquired by secondary endocytobiosis. The nucleomorph, the vestigial nucleus of the eukaryotic endosymbiont, harbors three linear chromosomes with a total coding capacity of 515 kb. Sequencing of the nucleomorph genome reveals that it encodes an ORF homologous to the bacterial cell division protein FtsZ, supporting the hypothesis that FtsZ is common in chloroplasts. We show that the nucleomorph-encoded ftsZ gene is transcribed. The transcript is polyadenylated and therefore shows features typical of eukaryotic transcripts. However, 3' processing of nucleomorph mRNA is inaccurate. Transcripts of nucleomorph genes in G. theta overlap with neighboring UTRs and coding regions. We demonstrate that the reading frame encoding NmFtsZ is not interrupted by introns. Subcellular localization of the protein reveals that FtsZ is localized exclusively in the chloroplast of G. theta, demonstrating that FtsZ is imported into the organelle.