scholarly journals Mg-Protoporphyrin IX and Heme Control HEMA, the Gene Encoding the First Specific Step of Tetrapyrrole Biosynthesis, in Chlamydomonas reinhardtii

2005 ◽  
Vol 4 (10) ◽  
pp. 1620-1628 ◽  
Author(s):  
Zinaida Vasileuskaya ◽  
Ulrike Oster ◽  
Christoph F. Beck
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Posttranscriptional Regulation ◽  
Higher Plants ◽  
Chlorophyll Biosynthesis ◽  
Single Gene ◽  
Protoporphyrin Ix ◽  
Tetrapyrrole Biosynthesis ◽  
Gene Encoding ◽  
Mrna Accumulation ◽  
Specific Step

ABSTRACT HEMA encodes glutamyl-tRNA reductase (GluTR), which catalyzes the first step specific for tetrapyrrole biosynthesis in plants, archaea, and most eubacteria. In higher plants, GluTR is feedback inhibited by heme and intermediates of chlorophyll biosynthesis. It plays a key role in controlling flux through the tetrapyrrole biosynthetic pathway. This enzyme, which in Chlamydomonas reinhardtii is encoded by a single gene (HEMA), exhibits homology to GluTRs of higher plants and cyanobacteria. HEMA mRNA accumulation was inducible not only by light but also by treatment of dark-adapted cells with Mg-protoporphyrin IX (MgProto) or hemin. The specificity of these tetrapyrroles as inducers was demonstrated by the absence of induction observed upon the feeding of protoporphyrin IX, the precursor of both heme and MgProto, or chlorophyllide. The HEMA mRNA accumulation following treatment of cells with light and hemin was accompanied by increased amounts of GluTR. However, the feeding of MgProto did not suggest a role for Mg-tetrapyrroles in posttranscriptional regulation. The induction by light but not that by the tetrapyrroles was prevented by inhibition of cytoplasmic protein synthesis. Since MgProto is synthesized exclusively in plastids and heme is synthesized in plastids and mitochondria, the data suggest a role of these compounds as organellar signals that control expression of the nuclear HEMA gene.

scholarly journals Structure of GUN4 fromChlamydomonas reinhardtii

2015 ◽  
Vol 71 (8) ◽  
pp. 1094-1099 ◽  
Author(s):  
Shabnam Tarahi Tabrizi ◽  
David B. Langley ◽  
Stephen J. Harrop ◽  
Anthony P. Duff ◽  
Robert D. Willows
Keyword(s):  
Crystal Structure ◽  
Chlamydomonas Reinhardtii ◽  
Chlorophyll Biosynthesis ◽  
Conformational Dynamics ◽  
Protoporphyrin Ix ◽  
Biosynthesis Pathway ◽  
Broad Agreement ◽  
Binding Cleft ◽  
Mg Chelatase

The genomes uncoupled 4 (GUN4) protein stimulates chlorophyll biosynthesis by increasing the activity of Mg-chelatase, the enzyme that inserts magnesium into protoporphyrin IX (PPIX) in the chlorophyll biosynthesis pathway. One of the roles of GUN4 is in binding PPIX and Mg-PPIX. In eukaryotes, GUN4 also participates in plastid-to-nucleus signalling, although the mechanism for this is unclear. Here, the first crystal structure of a eukaryotic GUN4, fromChlamydomonas reinhardtii, is presented. The structure is in broad agreement with those of previously solved cyanobacterial structures. Most interestingly, conformational divergence is restricted to several loops which cover the porphyrin-binding cleft. The conformational dynamics suggested by this ensemble of structures lend support to the understanding of how GUN4 binds PPIX or Mg-PPIX.

Isolation and Characterization of a Chlamydomonas reinhardtii Mutant Resistant to Photobleaching Herbicides

1993 ◽  
Vol 48 (3-4) ◽  
pp. 339-344 ◽  
Author(s):  
Hiromichi Oshio ◽  
Hideyuki Shibata ◽  
Nobuaki Mito ◽  
Masako Yamamoto ◽  
Elizabeth H. Harris ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Oxidase Activity ◽  
Higher Plants ◽  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Nuclear Genome ◽  
Photosynthetic Electron Transport ◽  
Wild Type ◽  
Protoporphyrinogen Oxidase ◽  
Isolation And Characterization

A group of highly active N -phenylimide photobleaching herbicides have been synthesized. These N -phenylimide herbicides as well as diphenyl ether herbicides induce protoporphyrin IX accumulation and inhibit protoporphyrinogen oxidase activity at extremely low concentrations in higher plants. The binding of a 14C -labeled N -phenylimide herbicide S-23121 [N-[4-chloro- 2-fluoro-5-[(1-m ethyl-2-propynyl)oxy]phenyl]-3,4,5,6-tetrahydrophthalimide] to the solubilized plastid fractions of greening corn seedlings is competed by the diphenyl ether herbicide acifluorfen-ethyl, but not by diuron, an inhibitor of photosynthetic electron transport. These results indicate a similar mode of action for both N -phenylimide and diphenyl ether herbicides.In order to investigate the mechanism of photobleaching herbicides at the molecular level, a strain of Chlamydomonas reinhardtii RS-3 resistant to N -phenylimide S-23142 [N -(4-chloro- 2-fluoro-5-propargyloxyphenyl)-3,4,5,6-tetrahydrophthalimide] was isolated by mutagenesis with N -m ethyl-N′-nitro-N -nitrosoguanidine. The 90% inhibition concentration of N -phenylimide S-23142 for growth of RS-3 was 100 times higher than that for wild type. Maximum accumulation of protoporphyrin IX was reached at 0.03 μᴍ of S-23142 for the wild type and 3 μᴍ for RS-3. RS-3 was resistant to oxadiazon, oxyfluorfen and acifluorfen-ethyl which had been shown to have the same mechanism of action as N -phenylimide herbicides, but not to paraquat, diuron or fluridone. Genetic analysis of RS-3 strain showed that the resistance results from a dominant mutation ( rs-3) in the nuclear genome. The magnesium protoporphyrin IX synthesizing activity from 5-am inolevulinic acid in chloroplast fragments isolated from RS-3 was less sensitive to S-23142 than that from wild type (CC-407). Protoporphyrinogen oxidase activity in Percoll™ -purified chloroplasts from RS-3 was also less sensitive to S-23142 than that from wild type. These results indicate that the resistance of RS-3 is specific for photobleaching herbicides, and that the mutation is related to protoporphyrinogen oxidase, the primary site of the photobleaching herbicide action.

Typical Peroxidative Parameters Verified with Mung-Bean Seedlings, Soybean Cells and Duckweed

1990 ◽  
Vol 45 (5) ◽  
pp. 512-517 ◽  
Author(s):  
Gerhard Sandmann ◽  
Beate Nicolaus ◽  
Peter Böger
Keyword(s):  
Preliminary Data ◽  
Mung Bean ◽  
Cell Membranes ◽  
Higher Plants ◽  
Chlorophyll Biosynthesis ◽  
Protoporphyrin Ix ◽  
Quantitative Relationship ◽  
Physiological Parameters ◽  
Short Chain ◽  
Protoporphyrinogen Oxidase

Peroxidation is indicated by several physiological parameters: (1) leakage of cell membranes and production of short-chain hydrocarbons, (2) degradation of cell constituents, (3) inhibition of chlorophyll biosynthesis, (4) accumulation of tetrapyrroles (protoporphyrin IX). (5) inhibition of protoporphyrinogen oxidase by peroxidizers, (6) alleviation of peroxidation by inhibitors of chlorophyll biosynthesis. (7) alleviation of peroxidation by photosynthesis inhibitors (“diuron effect”), (8) counteraction of the diuron effect by glucose (heterotrophic conditions). Such parameters, described and elaborated with microalgae and higher plants, arc verified in this study with soybean cells, duckweed and mung beans. Preliminary data indicate lack of quantitative relationship between inhibition of protoporphyrinogen oxidase, protoporphyrin (IX) formation and peroxidative consequences.

scholarly journals Identification and molecular characterization of a novel Chlamydomonas reinhardtii mutant defective in chlorophyll biosynthesis

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 138 ◽  
Author(s):  
Phillip B Grovenstein ◽  
Darryel A Wilson ◽  
Cameron G Lennox ◽  
Katherine P Smith ◽  
Alisha A Contractor ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Insertional Mutagenesis ◽  
Chlorophyll Biosynthesis ◽  
Protoporphyrin Ix ◽  
Model Organism ◽  
Oxygenic Photosynthesis ◽  
Functional Roles ◽  
Protein Levels ◽  
In The Wild ◽  
Chl Biosynthesis

The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms and are synthesized via a common branched tetrapyrrole biosynthetic pathway. One of the enzymes in the pathway is Mg chelatase (MgChel) which inserts Mg2+ into protoporphyrin IX (PPIX, proto) to form magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. MgChel is a multimeric enzyme that consists of three subunits designated CHLD, CHLI and CHLH. Plants have two isozymes of CHLI (CHLI1 and CHLI2) which are 70%-81% identical in protein sequences. Although the functional role of CHLI1 is well characterized, that of CHLI2 is not. We have isolated a non-photosynthetic light sensitive mutant 5A7 by random DNA insertional mutagenesis that is devoid of any detectable Chl. PCR based analyses show that 5A7 is missing the CHLI1 gene and at least eight additional functionally uncharacterized genes. 5A7 has an intact CHLI2 gene. Complementation with a functional copy of the CHLI1 gene restored Chl biosynthesis, photo-autotrophic growth and light tolerance in 5A7. We have identified the first chli1 mutant of Chlamydomonas reinhardtii and in green algae. Our results show that in the wild type Chlamydomonas CHLI2 protein amount is lower than that of CHLI1 and the chli1 mutant has a drastic reduction in CHLI2 protein levels although it possesses the CHLI2 gene. Our chli1 mutant opens up new avenues to explore the functional roles of CHLI1 and CHLI2 in Chl biosynthesis and chloroplast to nucleus retrograde signaling in Chlamydomonas, which has never been studied before.

scholarly journals Identification and molecular characterization of a novel Chlamydomonas reinhardtii mutant defective in chlorophyll biosynthesis

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 138
Author(s):  
Phillip B Grovenstein ◽  
Darryel A Wilson ◽  
Cameron G Lennox ◽  
Katherine P Smith ◽  
Alisha A Contractor ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Insertional Mutagenesis ◽  
Chlorophyll Biosynthesis ◽  
Protoporphyrin Ix ◽  
Model Organism ◽  
Oxygenic Photosynthesis ◽  
Functional Roles ◽  
Protein Levels ◽  
In The Wild ◽  
Chl Biosynthesis

The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms and are synthesized via a common branched tetrapyrrole biosynthetic pathway. One of the enzymes in the pathway is Mg chelatase (MgChel) which inserts Mg2+ into protoporphyrin IX (PPIX, proto) to form magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. MgChel is a multimeric enzyme that consists of three subunits designated CHLD, CHLI and CHLH. Plants have two isozymes of CHLI (CHLI1 and CHLI2) which are 70%-81% identical in protein sequences. Although the functional role of CHLI1 is well characterized, that of CHLI2 is not. We have isolated a non-photosynthetic light sensitive mutant 5A7 by random DNA insertional mutagenesis that is devoid of any detectable Chl. PCR based analyses show that 5A7 is missing the CHLI1 gene and at least eight additional functionally uncharacterized genes. 5A7 has an intact CHLI2 gene. Complementation with a functional copy of the CHLI1 gene restored Chl biosynthesis, photo-autotrophic growth and light tolerance in 5A7. We have identified the first chli1 (chli1-1) mutant of Chlamydomonas reinhardtii and in green algae. Our results show that in the wild type Chlamydomonas CHLI2 protein amount is lower than that of CHLI1 and the chli1-1 mutant has a drastic reduction in CHLI2 protein levels although it possesses the CHLI2 gene. Our chli1-1 mutant opens up new avenues to explore the functional roles of CHLI1 and CHLI2 in Chl biosynthesis in Chlamydomonas, which has never been studied before.

Structure, expression, chromosomal location and product of the gene encoding Adh2 in Petunia.

Genetics ◽  
1993 ◽  
Vol 133 (4) ◽  
pp. 999-1007
Author(s):  
R G Gregerson ◽  
L Cameron ◽  
M McLean ◽  
P Dennis ◽  
J Strommer
Keyword(s):  
Chromosomal Location ◽  
Higher Plants ◽  
Gene Encoding ◽  
Genomic Libraries ◽  
Regulatory Strategy ◽  
Adh1 Gene ◽  
Adh Genes ◽  
Genes Encoding ◽  
Adh Gene ◽  
Polymerase Chain

Abstract In most higher plants the genes encoding alcohol dehydrogenase comprise a small gene family, usually with two members. The Adh1 gene of Petunia has been cloned and analyzed, but a second identifiable gene was not recovered from any of three genomic libraries. We have therefore employed the polymerase chain reaction to obtain the major portion of a second Adh gene. From sequence, mapping and northern data we conclude this gene encodes ADH2, the major anaerobically inducible Adh gene of Petunia. The availability of both Adh1 and Adh2 from Petunia has permitted us to compare their structures and patterns of expression to those of the well-studied Adh genes of maize, of which one is highly expressed developmentally, while both are induced in response to hypoxia. Despite their evolutionary distance, evidenced by deduced amino acid sequence as well as taxonomic classification, the pairs of genes are regulated in strikingly similar ways in maize and Petunia. Our findings suggest a significant biological basis for the regulatory strategy employed by these distant species for differential expression of multiple Adh genes.

Subfunctionalization of Duplicate mitf Genes Associated With Differential Degeneration of Alternative Exons in Fish

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 259-267 ◽  
Author(s):  
Joachim Altschmied ◽  
Jacqueline Delfgaauw ◽  
Brigitta Wilde ◽  
Jutta Duschl ◽  
Laurence Bouneau ◽  
...  
Keyword(s):  
Danio Rerio ◽  
Evolutionary History ◽  
Single Gene ◽  
Regulatory Elements ◽  
Fugu Rubripes ◽  
Gene Encoding ◽  
Tetraodon Nigroviridis ◽  
Mammalian Lineage ◽  
History Of ◽  
Fish Proteins

Abstract The microphthalmia-associated transcription factor (MITF) exists in at least four isoforms. These are generated in higher vertebrates using alternative 5′ exons and promoters from a single gene. Two separate genes (mitf-m and mitf-b), however, are present in different teleost fish species including the poeciliid Xiphophorus, the pufferfishes Fugu rubripes and Tetraodon nigroviridis, and the zebrafish Danio rerio. Fish proteins MITF-m and MITF-b correspond at both the structural and the expression levels to one particular bird/mammalian MITF isoform. In the teleost lineage subfunctionalization of mitf genes after duplication at least 100 million years ago is associated with the degeneration of alternative exons and, probably, regulatory elements and promoters. For example, a remnant of the first exon specific for MITF-m is detected within the pufferfish gene encoding MITF-b. Retracing the evolutionary history of mitf genes in vertebrates uncovered the differential recruitment of new introns specific for either the teleost or the bird/mammalian lineage.

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