Bioengineering of photosynthetic membranes. Requirement of magnesium for the conversion of chlorophyllide a to chlorophyll a during the greening of etiochloroplasts in vitro

Daniell, Henry; Rebeiz, Constantin A.

doi:10.1002/bit.260260512

Cited by 15 publications

(7 citation statements)

References 16 publications

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“…18 Deluged with large amounts of ALA, the Chi biosynthetic machinery of the etiolated plants was forced to convert the ALA to Mg-protoporphyrins and Pchls in darkness and the latter to chlorophyllides and Chi in light. 20 " 22 As a consequence of the above-considerations and of the known photodynamic effects of tetrapyrroles (vide supra), ALA appeared to be the perfect candidate for a novel herbicide. Furthermore, since ALA was a natural amino acid that occurred in all living cells and was an integral part of the food chain, its environmental impact was expected to be minimal.…”

mentioning

confidence: 98%

Photodynamic herbicides. Recent developments and molecular basis of selectivity

Rebeiz

Montazer-Zouhoor

Mayasich

et al. 1988

Critical Reviews in Plant Sciences

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mentioning

confidence: 98%

Photodynamic herbicides. Recent developments and molecular basis of selectivity

Rebeiz

Montazer-Zouhoor

Mayasich

et al. 1988

Critical Reviews in Plant Sciences

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“…Plastids poised in the DV Pchlide biosynthetic mode were isolated either from green photoperiodically grown tissues or from etiolated tissues partially greened for 5 h under white fluorescent light (4) (vide supra). Plastids were isolated as described elsewhere (7,17).…”

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confidence: 99%

Chloroplast Biogenesis 60

Tripathy¹,

Rebeiz²

1988

Plant Physiol.

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In higher plants, most Photobiology, ABL, University of Illinois, Urbana, monocarboxylic biosynthetic route is not as preponderant as the DV monocarboxylic route, the DV and MV monocarboxylic routes were found to be weakly interconnected (15,17). From in vitro investigations, the DV and MV monocarboxylic routes did not appear to be interconnected at the level of Pchlide, either in etiolated barley or in etiolated cucumber (15,17). Indeed, although it is firmly believed that DV Pchlide is convertible to MV Pchlide in higher plants (5) by conversion of the vinyl group at position 4 of the macrocycle to an ethyl group (Fig. 1), this hypothesis has not yet been corroborated by experimental evidence (15, 17). During ongoing investigations of the regulation of the MV and DV Chl monocarboxylic biosynthetic routes in higher plants, preliminary experimental evidence suggested that in some plant species, DV Pchlide may be convertible to MV Pchlide, under certain conditions.In this work, it is shown that during the transition from the DV Pchlide to the MV Pchlide biosynthetic state, DV Pchlide can be partially converted to MV Pchlide in barley, a DMV/ LDV plant species. Under similar incubation conditions, the conversion of DV Pchlide to MV Pchlide did not appear to take place in cucumber, a DDV/LDV plant species. The discovery of the ubiquitous occurrence of DV3 and MV Pchlides in higher plants (1, 3) has led to a reevaluation of the Chl biosynthetic pathway (14). Protochlorophyllide is the main precursor of Chl in green plants. Considerable experimental evidence now indicates that, in higher plants, MV and DV Pchlides are formed from MV and DV Proto, respectively. via two parallel MV and DV monocarboxylic Chl biosynthetic routes (15,17).Furthermore, on the basis of the MV or DV monocarboxylic biosynthetic routes that predominate at night or in daylight, higher plants have been observed to fall into one of four greening groups (3, 4, 15), namely: dark divinylllight divinyl (DDV/LDV), dark monovinyl/light monovinyl (DMV/LMV), DMV/LDV, and DDV/ LMV. It has also been demonstrated that in etiolated DMV/ LDV plant species such as barley, which are poised in the MV Pchlide biosynthetic mode (3, 4), the DV and MV monocarboxylic biosynthetic routes are strongly interconnected prior to DV Pchlide formation (15, 17). On the other hand, in etiolated DDV/LDV plant species such as cucumber in which the MV '

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“…This process offers definite advantages in the cell environment where diffusion coefficients for substrate molecules the size of porphyrins (about 700 in mol wt) may be one-fifth those in H20 and would result in a considerable slowing down of enzymatic reaction rates (29). The rates of ALA conversion to Proto by the membrane bound enzymes observed after plastid lysis and isolation of the plastid membranes (Table III) were high enough to support the highest rates of ALA conversion to Pchlide (150-290 nmol/100 mg protein) which were reported by Daniell and Rebeiz (7) in isolated etiochloroplasts. Although the efficiency of ALA to Proto conversion reported in this work for isolated plastid membranes is compatible with the existence of the ALA to Proto enzymes as a multienzyme complex, more kinetic information is needed before a conclusive statement addressing this question is made.…”

Section: Discussionmentioning

confidence: 56%

“…The high Mg2' and NAD' concentrations used in the lysing medium were the same as those needed for high conversion rates of ALA to Mg-tetrapyrroles in vitro (7). It (6), leads to the conclusion that Pchlide is much more deeply embedded in the plastid membranes than the ALA to Proto enzymes which appear to be loosely associated with the surface of the membranes (Table III).…”

Section: Discussionmentioning

confidence: 97%

Intraplastidic Localization of the Enzymes That Convert δ-Aminolevulinic Acid to Protoporphyrin IX in Etiolated Cucumber Cotyledons

Lee¹,

Ball²,

Rebeiz³

1991

Plant Physiol.

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The intraplastidic localization of the enzymes that catalyze the conversion of 6-aminolevulinic acid (ALA) to protoporphyrin IX (Proto) is a controversial issue. While some researchers assign a stromal location for these enzymes, others favor a membranebound one. Etiochloroplasts were isolated from etiolated cucumber cotyledons (Cucumis sativus, L.) by differential centrifugation and were purified further by Percoll density gradient centrifugation. Purified plastids were highly intact, and contamination by other subcellular organelles was reduced five-to ninefold in comparison to crude plastid preparations. Most of the ALA to Proto conversion activity was found in the plastids. On a unit protein basis, the ALA to Proto conversion activity of isolated mitochondria was about 2% that of the purified plastids, and could be accounted for by contamination of the mitochondrial preparation by plastids. Lysis of the purified plastids by osmotic shock followed by high speed centrifugation, yielded two subplastidic fractions: a soluble clear stromal fraction and a pelleted yellowish one. The stromal fraction contained about 11% of the plastidic ALA to Proto conversion activity while the membrane fraction contained the remaining 89%. The stromal ALA to Proto conversion activity was in the range of stroma contamination by subplastidic membrane material. Complete solubilization of the ALA to Proto activity was achieved by high speed shearing and cavitation, in the absence of detergents. Solubilization of the ALA to Proto conversion activity was accompanied by release of about 30% of the membrane-bound protochlorophyllide. It is proposed that the enzymes that convert ALA to Proto are loosely associated with the plastid membranes and may be solubilized without the use of detergents. It is not clear at this stage whether the enzymes are associated with the outer or inner plastid membranes and whether they form a multienzyme complex or not.It is presently acknowledged that the enzymes that convert ALA3 to protochlorophyll(ides) and Chl are located in the plastids (5,6,20,22,23). The intraplastidic localization of

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Bioengineering of photosynthetic membranes. Requirement of magnesium for the conversion of chlorophyllide a to chlorophyll a during the greening of etiochloroplasts in vitro

Cited by 15 publications

References 16 publications

Photodynamic herbicides. Recent developments and molecular basis of selectivity

Photodynamic herbicides. Recent developments and molecular basis of selectivity

Chloroplast Biogenesis 60

Intraplastidic Localization of the Enzymes That Convert δ-Aminolevulinic Acid to Protoporphyrin IX in Etiolated Cucumber Cotyledons

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