The common origins of the pigments of life?early steps of chlorophyll biosynthesis

Avissar, Yael J.; Moberg, Patricia A.

doi:10.1007/bf00048596

Cited by 26 publications

(14 citation statements)

References 202 publications

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“…While genes involved in the vitB 12 and Bchl synthesis are found in large operons, genes encoding the enzymes involved in heme synthesis are scattered over the genome (Young et al 1989, McGoldrick et al 2002, Warren et al 2002, Smart, Willett and Bauer 2004). This feature is not unusual, though a few organisms show an operon organization for some of their hem genes (Avissar and Moberg 1995). The one exception in R. capsulatus are the hemC and hemE genes that are divergently transcribed and separated by 111 bp (Smart, Willett and Bauer 2004).…”

Section: Topology Of Genes Involved In Synthesis Of Tetrapyrrolesmentioning

confidence: 99%

The Tetrapyrrole Biosynthetic Pathway and Its Regulation in Rhodobacter capsulatus

Zappa

Bauer

2010

Advances in Experimental Medicine and Biology

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The purple anoxygenic photosynthetic bacterium Rhodobacter capsulatus is capable of growing in aerobic or anaerobic conditions, in the dark or using light, etc. Achieving versatile metabolic adaptations from respiration to photosynthesis requires the use of tetrapyrroles such as heme and bacteriochlorophyll, in order to carry oxygen, to transfer electrons and to harvest light energy. A third tetrapyrrole, cobalamin (vitamin B12), is synthesized and used as a cofactor for many enzymes. Heme, bacteriochlorophyll and vitamin B12 constitute three major end products of the tetrapyrrole biosynthetic pathway in purple bacteria. Their respective synthesis involves a plethora of enzymes several that have been characterized and several that are uncharacterized as described in this review. To respond to changes in metabolic requirements the pathway undergoes complex regulation to direct the flow of tetrapyrrole intermediates into a specific branch(s) at the expense other branches of the pathway. Transcriptional regulation of the tetrapyrrole synthesizing enzymes by redox conditions and pathway intermediates is reviewed. In addition, we discus the involvement of several transcription factors (RegA, CrtJ, FnrL, AerR, HbrL, Irr) as well as the role of riboswitches. Finally, the interdependence of the tetrapyrrole branches on each others synthesis is discussed.

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Section: Topology Of Genes Involved In Synthesis Of Tetrapyrrolesmentioning

confidence: 99%

The Tetrapyrrole Biosynthetic Pathway and Its Regulation in Rhodobacter capsulatus

Zappa

Bauer

2010

Advances in Experimental Medicine and Biology

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“…1. Readers are referred to several recent reviews for further information on the early steps of tetrapyrrole biosynthesis starting with production of ALA through protoporphyrin IX (PIX) (Avissar and Moberg 1995;Jaffe 2003Jaffe , 2004Shoolingin-Jordan 2003).…”

Section: Introductionmentioning

confidence: 99%

Recent advances in chlorophyll biosynthesis

Bollivar

2006

Photosynth Res

106

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The importance of chlorophyll (Chl) to the process of photosynthesis is obvious, and there is clear evidence that the regulation of Chl biosynthesis has a significant role in the regulation of assembly of the photosynthetic apparatus. The understanding of Chl biosynthesis has rapidly advanced in recent years. The identification of genetic loci associated with each of the biochemical steps has been accompanied by a greater appreciation of the role of Chl biosynthesis intermediates in intracellular signaling. The purpose of this review is to provide a source of information for all the steps in Chl and bacteriochlorophyll a biosynthesis, with an emphasis on steps that are believed to be key regulation points.

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“…Tetrapyrroles, in particular chlorophylls and hemes, are essential components of such fundamental processes as photosynthesis and respiration, and hence have been addressed as "pigments of life" (Avissar and Moberg 1995). Besides their life-supporting role, tetrapyrroles can also be lethal for cells: metal-free porphyrins and their Mg-complexes are potent photo-sensitizers that catalyze formation of toxic singlet oxygen in the presence of air and light.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of lycopene cyclase results in accumulation of chlorophyll precursors

Rocca

Rascio

Oster³

et al. 2006

Planta

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Free porphyrins and their magnesium complexes, including chlorophylls, are potent photo-sensitizers. Plants usually accumulate these compounds bound to proteins together with protective compounds like carotenoids. Besides their protective role, carotenoids can play a structural role in these complexes. To analyze the effect of impaired carotenogenesis on plastid membranes we applied to barley seedlings the bleaching herbicide 2-(4-chlorophenylthio)triethylamine (CPTA) as a specific inhibitor for the cyclization of lycopene. To avoid interference with photo-oxidation, the essential experiments were performed on seedlings grown in darkness. While the amount of total carotenoids decreased, we found accumulation of more 6-carotene than lycopene in darkness clearly showing that CPTA inhibits the lycopene beta-cyclase more effectively than the lycopene epsilon-cyclase. The CPTA treatment resulted in accumulation of non-photoactive protochlorophyllide a; the amount of photoactive protochlorophyllide and NADPH:protochlorophyllide oxidoreductase remained constant. Further, the level of Mg protophorphyrin and its monomethyl ester increased to an extent similar to that obtained by application of 5-aminolevulinic acid (ALA). The perturbation of the ultrastructure of etioplast inner membranes, observed after CPTA-treatment, was not found after ALA-treatment; this excluded the accumulated tetrapyrroles as responsible for the perturbation. By contrast, the down-regulation of Lhcb and RbcS genes found after CPTA-treatment was compatible with the presumed role of Mg protophorphyrin as "plastid signal" for regulation of nuclear gene expression. Possible mechanisms for enhancement of tetrapyrrole accumulation by non-cyclic carotenoids are discussed.

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The common origins of the pigments of life?early steps of chlorophyll biosynthesis

Cited by 26 publications

References 202 publications

The Tetrapyrrole Biosynthetic Pathway and Its Regulation in Rhodobacter capsulatus

The Tetrapyrrole Biosynthetic Pathway and Its Regulation in Rhodobacter capsulatus

Recent advances in chlorophyll biosynthesis

Inhibition of lycopene cyclase results in accumulation of chlorophyll precursors

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