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Visualization of a cytoskeleton-like FtsZ network in chloroplasts.

Kiessling J, Kruse S, Rensing SA, Harter K, Decker EL, Reski R - J. Cell Biol. (2000)

Bottom Line: It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton.Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure.As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

View Article: PubMed Central - PubMed

Affiliation: University of Freiburg, Plant Biotechnology, D-79104 Freiburg, Germany.

ABSTRACT
It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

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Subcellular localization of FtsZ-GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with the corresponding expression plasmid and GFP fluorescence was visualized by CLSM 2 d after transfection. (a) Protoplast transfected with PpFtsZ1-GFP. (b) Protoplast transfected with PpFtsZ2-GFP. (c) Single chloroplast (detail of a). (d–g) Sections of the chloroplast shown in c demonstrating the localization of PpFtsZ1 solely within chloroplasts. (h) Protoplast transfected with pFtsZ1(1–35)-GFP (incomplete transit peptide) showing cytoplasmic distribution of fusion protein. (i) Protoplast transfected with pFtsZ1(1–93)-GFP (complete transit peptide) showing plastidic distribution of fusion protein. a–c, and h and i, represent overlays of all sections of the object. Chlorophyll fluorescence is shown in red; GFP signals are shown in green. Bars, 5 μm.
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Figure 2: Subcellular localization of FtsZ-GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with the corresponding expression plasmid and GFP fluorescence was visualized by CLSM 2 d after transfection. (a) Protoplast transfected with PpFtsZ1-GFP. (b) Protoplast transfected with PpFtsZ2-GFP. (c) Single chloroplast (detail of a). (d–g) Sections of the chloroplast shown in c demonstrating the localization of PpFtsZ1 solely within chloroplasts. (h) Protoplast transfected with pFtsZ1(1–35)-GFP (incomplete transit peptide) showing cytoplasmic distribution of fusion protein. (i) Protoplast transfected with pFtsZ1(1–93)-GFP (complete transit peptide) showing plastidic distribution of fusion protein. a–c, and h and i, represent overlays of all sections of the object. Chlorophyll fluorescence is shown in red; GFP signals are shown in green. Bars, 5 μm.

Mentions: Because in vitro as well as in silico studies are indirect and may easily generate contradictory and inconclusive data, we analyzed subcellular localization of both Physcomitrella FtsZ proteins in vivo as COOH-terminal GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with expression plasmids PpFtsZ1-GFP or PpFtsZ2-GFP, respectively, and GFP fluorescence was visualized by CLSM. 2 d after transfection, GFP signals could be solely detected within plastids (Fig. 2, a–g). The absence of GFP fluorescence in all other cell compartments, including the plastid outer membrane, was confirmed by series of optical sections through protoplasts and single plastids (Fig. 2, d–g), respectively.


Visualization of a cytoskeleton-like FtsZ network in chloroplasts.

Kiessling J, Kruse S, Rensing SA, Harter K, Decker EL, Reski R - J. Cell Biol. (2000)

Subcellular localization of FtsZ-GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with the corresponding expression plasmid and GFP fluorescence was visualized by CLSM 2 d after transfection. (a) Protoplast transfected with PpFtsZ1-GFP. (b) Protoplast transfected with PpFtsZ2-GFP. (c) Single chloroplast (detail of a). (d–g) Sections of the chloroplast shown in c demonstrating the localization of PpFtsZ1 solely within chloroplasts. (h) Protoplast transfected with pFtsZ1(1–35)-GFP (incomplete transit peptide) showing cytoplasmic distribution of fusion protein. (i) Protoplast transfected with pFtsZ1(1–93)-GFP (complete transit peptide) showing plastidic distribution of fusion protein. a–c, and h and i, represent overlays of all sections of the object. Chlorophyll fluorescence is shown in red; GFP signals are shown in green. Bars, 5 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169431&req=5

Figure 2: Subcellular localization of FtsZ-GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with the corresponding expression plasmid and GFP fluorescence was visualized by CLSM 2 d after transfection. (a) Protoplast transfected with PpFtsZ1-GFP. (b) Protoplast transfected with PpFtsZ2-GFP. (c) Single chloroplast (detail of a). (d–g) Sections of the chloroplast shown in c demonstrating the localization of PpFtsZ1 solely within chloroplasts. (h) Protoplast transfected with pFtsZ1(1–35)-GFP (incomplete transit peptide) showing cytoplasmic distribution of fusion protein. (i) Protoplast transfected with pFtsZ1(1–93)-GFP (complete transit peptide) showing plastidic distribution of fusion protein. a–c, and h and i, represent overlays of all sections of the object. Chlorophyll fluorescence is shown in red; GFP signals are shown in green. Bars, 5 μm.
Mentions: Because in vitro as well as in silico studies are indirect and may easily generate contradictory and inconclusive data, we analyzed subcellular localization of both Physcomitrella FtsZ proteins in vivo as COOH-terminal GFP fusion proteins. Physcomitrella protoplasts were transiently transfected with expression plasmids PpFtsZ1-GFP or PpFtsZ2-GFP, respectively, and GFP fluorescence was visualized by CLSM. 2 d after transfection, GFP signals could be solely detected within plastids (Fig. 2, a–g). The absence of GFP fluorescence in all other cell compartments, including the plastid outer membrane, was confirmed by series of optical sections through protoplasts and single plastids (Fig. 2, d–g), respectively.

Bottom Line: It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton.Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure.As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

View Article: PubMed Central - PubMed

Affiliation: University of Freiburg, Plant Biotechnology, D-79104 Freiburg, Germany.

ABSTRACT
It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

Show MeSH
Related in: MedlinePlus