The dynamic surface of dividing cyanelles and ultrastructure of the region directly below the surface in Cyanophora paradoxa

Sato, Mayuko; Mogi, Yuko; Nishikawa, Toshikazu; Miyamura, Shinichi; Nagumo, Tamotsu; Kawano, Shigeyuki

doi:10.1007/s00425-008-0872-4

Cited by 36 publications

(33 citation statements)

References 46 publications

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Section: Discussionmentioning

confidence: 99%

“…The FtsZ ring and the inner PD ring were detected at the chloroplast division site (41,42). However, the outer PD ring was not evident (41,42), and DRP5B is not encoded in the C. paradoxa genome (43). It has been suggested that the constriction of the division site is accompanied by an ingrowth and subsequent degradation of the PG layer at the division site in glaucophyte chloroplast division, as in bacterial cell division (41,43).…”

Section: Discussionmentioning

confidence: 99%

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Chloroplast division checkpoint in eukaryotic algae

Sumiya

Fujiwara

Era

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Chloroplasts evolved from a cyanobacterial endosymbiont. It is believed that the synchronization of endosymbiotic and host cell division, as is commonly seen in existing algae, was a critical step in establishing the permanent organelle. Algal cells typically contain one or only a small number of chloroplasts that divide once per host cell cycle. This division is based partly on the S-phase-specific expression of nucleus-encoded proteins that constitute the chloroplast-division machinery. In this study, using the red alga Cyanidioschyzon merolae, we show that cell-cycle progression is arrested at the prophase when chloroplast division is blocked before the formation of the chloroplastdivision machinery by the overexpression of Filamenting temperaturesensitive (Fts) Z2-1 (Fts72-1), but the cell cycle progresses when chloroplast division is blocked during division-site constriction by the overexpression of either FtsZ2-1 or a dominant-negative form of dynamin-related protein 5B (DRP5B). In the cells arrested in the prophase, the increase in the cyclin B level and the migration of cyclin-dependent kinase B (CDKB) were blocked. These results suggest that chloroplast division restricts host cell-cycle progression so that the cell cycle progresses to the metaphase only when chloroplast division has commenced. Thus, chloroplast division and host cell-cycle progression are synchronized by an interactive restriction that takes place between the nucleus and the chloroplast. In addition, we observed a similar pattern of cell-cycle arrest upon the blockage of chloroplast division in the glaucophyte alga Cyanophora paradoxa, raising the possibility that the chloroplast division checkpoint contributed to the establishment of the permanent organelle.chloroplast division | algal cell cycle | Cyanidioschyzon merolae | Cyanophora paradoxa C hloroplasts trace their origin to a primary endosymbiotic event that took place more than a billion years ago, a process in which an ancestral cyanobacterium became integrated into a previously nonphotosynthetic eukaryote. The ancient alga that resulted from this primary endosymbiotic event evolved into the Glaucophyta (glaucophyte algae), Rhodophyta (red algae), and Viridiplantae (green algae, streptophyte algae, and land plants), which together are grouped as the Plantae (sensu stricto) or Archaeplastida. After these primitive green and red algae had become established, chloroplasts then spread into other eukaryote lineages through secondary endosymbiotic events in which a red or green alga became integrated into previously nonphotosynthetic eukaryotes (1).The continuity of chloroplasts has been maintained for more than a billion years. The majority of algae (both unicellular and multicellular, with both possessing chloroplasts of primary and secondary endosymbiotic origin) have one or at most only a few chloroplasts per cell. Thus, chloroplast division is synchronized with the host cell cycle so that the chloroplast divides before cytokinesis and is thus transmitted into each daughter cell ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Chloroplast division checkpoint in eukaryotic algae

Sumiya

Fujiwara

Era

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…FE-SEM was performed as described by Sato et al (2009) with minor modifications. Cells were subjected to double fixation using 2% glutaraldehyde and 1% osmium tetroxide as described previously (Matsuzaki et al 2010).…”

Section: Methodsmentioning

confidence: 99%

“…Sato et al (2009) showed the clear plastid surface of C. paradoxa under ultra-high resolution FE-SEM. However, the surface ornamentations of the vegetative cells of Cyanophora have not been examined using ultra-high resolution FE-SEM.…”

mentioning

confidence: 96%

Surface Ornamentation of <i>Cyanophora paradoxa</i> (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

et al. 2014

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Summary Cyanophora paradoxa is an enigmatic biflagellate that may represent the first photosynthetic eukaryote morphologically. This alga has been widely studied as a model organism of primitive phototrophs. However, surface ornamentations of the vegetative cells have not been examined using ultra-high resolution field emission (FE) scanning electron microscopy (SEM). In the present study, C. paradoxa NIES-547 vegetative cells were examined using FE-SEM and compared with the data using conventional SEM. Our FE-SEM images demonstrated that the cell surface was ornamented with angular fenestrations framed by ridges. In contrast, conventional SEM did not reveal similar surface ornamentation. Transmission electron microscopy showed the ridge was formed by the edges of overlapping or attaching outermost plate vesicles at the cell periphery.

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“…A recent study of MreBCD depletion mutants growing as large spheres provides convincing evidence for asymmetric constriction, with the constriction located at an arc of FtsZ (11). A dramatic example of asymmetric septation is seen in the division of the cyanelle, a primitive plastid of the protist Cyanophora paradoxa (165,166). The Z ring extends from onefourth to one-half way around the cell and is located over a very asymmetrically forming septum (Fig.…”

Section: Incomplete Ftsz Rings Can Generate Constrictionmentioning

confidence: 99%

FtsZ in Bacterial Cytokinesis: Cytoskeleton and Force Generator All in One

Erickson

Anderson

Osawa

2010

Microbiol Mol Biol Rev

557

752

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SUMMARY FtsZ, a bacterial homolog of tubulin, is well established as forming the cytoskeletal framework for the cytokinetic ring. Recent work has shown that purified FtsZ, in the absence of any other division proteins, can assemble Z rings when incorporated inside tubular liposomes. Moreover, these artificial Z rings can generate a constriction force, demonstrating that FtsZ is its own force generator. Here we review light microscope observations of how Z rings assemble in bacteria. Assembly begins with long-pitch helices that condense into the Z ring. Once formed, the Z ring can transition to short-pitch helices that are suggestive of its structure. FtsZ assembles in vitro into short protofilaments that are ∼30 subunits long. We present models for how these protofilaments might be further assembled into the Z ring. We discuss recent experiments on assembly dynamics of FtsZ in vitro, with particular attention to how two regulatory proteins, SulA and MinC, inhibit assembly. Recent efforts to develop antibacterial drugs that target FtsZ are reviewed. Finally, we discuss evidence of how FtsZ generates a constriction force: by protofilament bending into a curved conformation.

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The dynamic surface of dividing cyanelles and ultrastructure of the region directly below the surface in Cyanophora paradoxa

Cited by 36 publications

References 46 publications

Chloroplast division checkpoint in eukaryotic algae

Chloroplast division checkpoint in eukaryotic algae

Surface Ornamentation of <i>Cyanophora paradoxa</i> (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

FtsZ in Bacterial Cytokinesis: Cytoskeleton and Force Generator All in One

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