Three-dimensional structure of the prolamellar body in squash etioplasts

Murakami, Satoru; Yamada, Naoko; Nagano, Misuzu; Osumi, Masako

doi:10.1007/bf01276336

Cited by 42 publications

(28 citation statements)

References 20 publications

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“…Like leucoplasts, the etioplasts are long, flexible plastids that lack the structural rigidity of chloroplasts. Etioplasts are characterized by the presence of amorphous prolamellar bodies (Gunning, 1965;Kahn, 1968;Mackender, 1978;Murakami et al, 1985;Gunning, 2001;Solymosi and Schoefs, 2010). Our electron microscopybased observations performed on plants that were grown under conditions defined in previous reports confirm these differences in internal membrane organization between chloroplasts and etioplasts.…”

Section: Discussion Plastid Fusion: Assumption Versus Evidencesupporting

confidence: 77%

Differential Coloring Reveals That Plastids Do Not Form Networks for Exchanging Macromolecules

et al. 2012

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Stroma-filled tubules named stromules are sporadic extensions of plastids. Earlier, photobleaching was used to demonstrate fluorescent protein diffusion between already interconnected plastids and formed the basis for suggesting that all plastids are able to form networks for exchanging macromolecules. However, a critical appraisal of literature shows that this conjecture is not supported by unequivocal experimental evidence. Here, using photoconvertible mEosFP, we created color differences between similar organelles that enabled us to distinguish clearly between organelle fusion and nonfusion events. Individual plastids, despite conveying a strong impression of interactivity and fusion, maintained well-defined boundaries and did not exchange fluorescent proteins. Moreover, the high pleomorphy of etioplasts from dark-grown seedlings, leucoplasts from roots, and assorted plastids in the accumulation and replication of chloroplasts5 (arc5), arc6, and phosphoglucomutase1 mutants of Arabidopsis thaliana suggested that a single plastid unit might be easily mistaken for interconnected plastids. Our observations provide succinct evidence to refute the long-standing dogma of interplastid connectivity. The ability to create and maintain a large number of unique biochemical factories in the form of singular plastids might be a key feature underlying the versatility of green plants as it provides increased internal diversity for them to combat a wide range of environmental fluctuations and stresses.

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Section: Discussion Plastid Fusion: Assumption Versus Evidencesupporting

confidence: 77%

Differential Coloring Reveals That Plastids Do Not Form Networks for Exchanging Macromolecules

et al. 2012

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“…The membrane architecture of prolamellar bodies has been analysed in detail by means of ultrathin sectioning (Wehrmeyer 1965a(Wehrmeyer -c, 1967Ikeda 1968;Gunning 1965;Gunning andSteer 1975, 1996;Hyde et al 1997), freeze fracture (Osumi et al 1984, Murakami et al 1985, X-ray diffraction (Williams et al 1998), and mathematical analysis (Israelachvili and Wolfe 1980, Charvolin and Sadoc 1996, Hyde et al 1997. The most common geometries are analogues of zincblende and wurtzite crystal lattices, first described in detail by Wehrmeyer (1965b, c) and Ikeda (1968) and consisting of tetrahedrally branched tubular membranes (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…A form based on hexahedrally branched tubules has also been detected, but the original idea (Gunning 1965) that sectioning it in various planes could account for the views now known to be based on tetrahedral units was wrong. In centric prolamellar bodies (Wehrmeyer 1965a) 20 tetrahedral blocks of membrane lattice of the zincblende form radiate from each vertex of a central pentagonal dodecahedron, joined smoothly to one another by interfaces of the wurtzite form (Murakami et al 1985, Gunning and Steer 1996, Charvolin and Sadoc 1996. In centric prolamellar bodies (Wehrmeyer 1965a) 20 tetrahedral blocks of membrane lattice of the zincblende form radiate from each vertex of a central pentagonal dodecahedron, joined smoothly to one another by interfaces of the wurtzite form (Murakami et al 1985, Gunning and Steer 1996, Charvolin and Sadoc 1996.…”

Section: Introductionmentioning

confidence: 99%

Membrane geometry of ?open? prolamellar bodies

Gunning

2001

Protoplasma

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The "open" type of prolamellar body in etiplasts was examined by electron microscopy to characterise its three-dimensional organisation. As in more compact forms of prolamellar body, its basic geometric unit is a tetrahedrally branched tubule. In the "open" type, these lie smoothly confluent with one another at the vertices of 5- and 6-membered rings which circumscribe the faces of three kinds of polyhedra: pentagonal dodecahedra (with 12 pentagonal faces), 14-hedra (2 opposite hexagonal faces joined by two circlets of six pentagonal faces), and 15-hedra (3 hexagonal and 12 pentagonal faces). These polyhedra join confluently in their turn, sharing faces with one another in at least one recognisable super-structure which accounts for the appearance of "open" prolamellar bodies in many ultrathin sections. In this organisation, columns of pentagonal dodecahedra are arranged at 120 degrees to one another in the x-y-plane of the lattice. They do not fill the plane but intersect so as to delimit voids in the form of hexagonally arranged 14-hedra (with hexagonal rings in the x-y-plane). Strata of this type alternate with strata made of face-sharing 15-hedra (with their hexagonal rings normal to x-y), which also delimit 14-hedra. The 14-hedra thus lie in register in the z-axis in hexagonally arranged columns, normal to the alternating strata. Other possible organisations cannot be excluded and local variations and dislocations certainly occur, but many micrographs that display elements of symmetry in "open" prolamellar bodies can be matched to thin slices through such a model. Its geometry is like that of the cages of water molecules in type IV (sensu Jeffrey = type III sensu O'Keeffe) clathrate-hydrates, point group P6/mmm, but about two orders of magnitude larger.

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“…At pH 7.5 (Fig. 7A), the majority of the PLB are in the form of highly ordered paracrystalline arrays based on networks of interconnected tubular tetrapodal membrane units forming a bicontinuous diamond cubic (Fd3m) lattice [21,22]. Resuspension at pH 6.5 ( Fig.…”

Section: Structural Studiesmentioning

confidence: 99%

The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays)

Selstam

Schelin

Brain

et al. 2002

European Journal of Biochemistry

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Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide 640 and POR-PChlide 650 (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide 650 to POR-PChlide 640 and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mM NADPH for POR-PChlide 640 reformation. The disappearance of PORPChlide 650 and the reorganization of the PLB, however, are irreversible. Restoration of low-pH treated PLB to pH 7.5 leads to a further breakdown down of the PLB membrane and no reformation of POR-PChlide 650 . Related spectral changes are seen in PLB aged at room temperature at pH 7.5 in NADPH-free assay medium. The reformation of PORPChlide 650 in this system is readily reversible on re-addition of NADPH with a half-saturation value about 1.0 lM. Comparison of the two sets of changes suggest a close link between the stability of the POR-PChlide 650 , membrane organization and NADPH binding.The low-pH driven spectral changes seen in maize PLB are shown to be accelerated by adenosine AMP, ADP and ATP. The significance of this is discussed in terms of current suggestions of the possible involvement of phosphorylation (or adenylation) in changes in the aggregational state of the POR complex.Keywords: protochlorophyllide oxidoreductase; prolamellar body; protochlorophyllide; oxidoreductase; chlorophyllide.Plant prolamellar bodies (PLB) found in the etioplasts of dark-grown (etiolated) seedlings, are the precursors of the chloroplast thylakoid membrane. The PLB membrane is dominated by the presence of a single protein species, protochlorophyllide oxidoreductase (EC 1.3.1.33) (POR) that catalyses the light-driven, NADPH-dependent reduction of protochlorophyllide (PChlide) to chlorophyllide (Chlide). Analyses of the absorption spectrum of PLB [1] and low-temperature fluorescence spectra of etioplast inner membrane preparations (EPIM) and PLB [2], indicate the presence of three major pools of PChlide; a nonphotoconvertible form PChlide 628)633 and two photoconvertible forms PChlide 640)645 and PChlide 650)657 . The suffix numbers relate to the wavelengths of the absorption and emission maxima, respectively. To emphasize the fact that the two photoconvertible forms are bound to POR, they will be referred to here to as POR-PChlide 640 and POR-PChlide 650 .Under in vivo conditions, exposure of etioplasts to a flash of bright white light leads to a conversion of the photoconvertible PChlide pigments to Chlide resulting in a rapid shift of the main absorption maximum from 650 nm, initially to about 678 nm and then to 684 nm. Over a period of about 20 min, this absorption maximum shifts back to 672 nm. This latter shift, r...

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Three-dimensional structure of the prolamellar body in squash etioplasts

Cited by 42 publications

References 20 publications

Differential Coloring Reveals That Plastids Do Not Form Networks for Exchanging Macromolecules

Differential Coloring Reveals That Plastids Do Not Form Networks for Exchanging Macromolecules

Membrane geometry of ?open? prolamellar bodies

The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays)

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