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Inheritance of the reduced mitochondria of Giardia intestinalis is coupled to the flagellar maturation cycle
BMC Biology ( IF 5.4 ) Pub Date : 2021-09-07 , DOI: 10.1186/s12915-021-01129-7
Pavla Tůmová 1 , Luboš Voleman 2 , Andreas Klingl 3 , Eva Nohýnková 1 , Gerhard Wanner 4 , Pavel Doležal 2
Affiliation  

The presence of mitochondria is a distinguishing feature between prokaryotic and eukaryotic cells. It is currently accepted that the evolutionary origin of mitochondria coincided with the formation of eukaryotes and from that point control of mitochondrial inheritance was required. Yet, the way the mitochondrial presence has been maintained throughout the eukaryotic cell cycle remains a matter of study. Eukaryotes control mitochondrial inheritance mainly due to the presence of the genetic component; still only little is known about the segregation of mitochondria to daughter cells during cell division. Additionally, anaerobic eukaryotic microbes evolved a variety of genomeless mitochondria-related organelles (MROs), which could be theoretically assembled de novo, providing a distinct mechanistic basis for maintenance of stable mitochondrial numbers. Here, we approach this problem by studying the structure and inheritance of the protist Giardia intestinalis MROs known as mitosomes. We combined 2D stimulated emission depletion (STED) microscopy and focused ion beam scanning electron microscopy (FIB/SEM) to show that mitosomes exhibit internal segmentation and conserved asymmetric structure. From a total of about forty mitosomes, a small, privileged population is harnessed to the flagellar apparatus, and their life cycle is coordinated with the maturation cycle of G. intestinalis flagella. The orchestration of mitosomal inheritance with the flagellar maturation cycle is mediated by a microtubular connecting fiber, which physically links the privileged mitosomes to both axonemes of the oldest flagella pair and guarantees faithful segregation of the mitosomes into the daughter cells. Inheritance of privileged Giardia mitosomes is coupled to the flagellar maturation cycle. We propose that the flagellar system controls segregation of mitochondrial organelles also in other members of this supergroup (Metamonada) of eukaryotes and perhaps reflects the original strategy of early eukaryotic cells to maintain this key organelle before mitochondrial fusion-fission dynamics cycle as observed in Metazoa was established.

中文翻译:

肠道贾第虫线粒体减少的遗传与鞭毛成熟周期有关

线粒体的存在是原核细胞和真核细胞之间的区别特征。目前公认的是,线粒体的进化起源与真核生物的形成同时发生,因此需要控制线粒体遗传。然而,在整个真核细胞周期中线粒体存在的方式仍然是一个研究问题。真核生物控制线粒体遗传主要是由于遗传成分的存在。关于细胞分裂过程中线粒体与子细胞的分离仍然知之甚少。此外,厌氧真核微生物进化出多种无基因组线粒体相关细胞器(MRO),理论上可以从头组装,为维持稳定的线粒体数量提供了独特的机制基础。在这里,我们通过研究称为线粒体的原生贾第鞭毛虫 MRO 的结构和遗传来解决这个问题。我们结合 2D 受激发射损耗 (STED) 显微镜和聚焦离子束扫描电子显微镜 (FIB/SEM) 来表明有丝分裂体表现出内部分割和保守的不对称结构。从总共大约 40 个有丝分裂体中,一小部分特权群体被利用到鞭毛装置,它们的生命周期与 G.肠球菌鞭毛的成熟周期相协调。有丝分裂体遗传与鞭毛成熟周期的协调是由微管连接纤维介导的,这在物理上将特权线粒体与最古老的鞭毛对的两个轴丝连接起来,并确保将线粒体忠实地分离到子细胞中。特权贾第虫线粒体的遗传与鞭毛成熟周期相结合。我们提出鞭毛系统也控制真核生物超群(Metamonada)的其他成员中线粒体细胞器的分离,这可能反映了早期真核细胞在线粒体融合 - 裂变动力学循环之前维持这一关键细胞器的原始策略,如在后生动物中观察到的那样已确立的。
更新日期:2021-09-07
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