Identification and molecular characterization of a novel Chlamydomonas reinhardtii mutant defective in chlorophyll biosynthesis
| Autor: | Darryel A Wilson, Phillip B Grovenstein, Surangi N. Perera, Kathryn D Lankford, Mautusi Mitra, Kelsey A. Gaston |
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| Rok vydání: | 2013 |
| Předmět: |
Genetics
General Immunology and Microbiology biology Chlamydomonas Mutant Wild type Chlamydomonas reinhardtii Articles General Medicine biology.organism_classification General Biochemistry Genetics and Molecular Biology Complementation Insertional mutagenesis Light intensity Biochemistry Plant Genetics & Gene Expression General Pharmacology Toxicology and Pharmaceutics Plant Biochemistry & Physiology Gene Research Article |
| Zdroj: | F1000Research |
| ISSN: | 2046-1402 |
| DOI: | 10.12688/f1000research.2-142.v2 |
| Popis: | The green micro-algaChlamydomonasreinhardtiiis an elegant model organism to study oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in photosynthesis and respiration. These tetrapyrroles are synthesized via a common branched pathway that involves mainly enzymes, encoded by nuclear genes. One of the enzymes in the pathway is Mg chelatase (MgChel). MgChel catalyzes insertion of Mg2+into protoporphyrin IX (PPIX, proto) to form Magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. The GUN4 (genomes uncoupled 4) protein is not essential for the MgChel activity but has been shown to significantly stimulate its activity. We have isolated a light sensitive mutant,6F14,by random DNA insertional mutagenesis.6F14cannot tolerate light intensities higher than 90-100 μmol photons m-2s-1. It shows a light intensity dependent progressive photo-bleaching.6F14is incapable of photo-autotrophic growth under light intensity higher than 100 μmol photons m-2s-1. PCR based analyses show that in6F14the insertion of the plasmid outside theGUN4locus has resulted in a genetic rearrangement of theGUN4gene and possible deletions in the genomic region flanking theGUN4gene. Ourgun4mutant has a Chl content very similar to that in the wild type in the dark and is very sensitive to fluctuations in the light intensity in the environment unlike the earlier identifiedChlamydomonas gun4mutant. Complementation with a functional copy of theGUN4gene restored light tolerance, Chl biosynthesis and photo-autotrophic growth under high light intensities in6F14.6F14is the secondgun4mutant to be identified inC. reinhardtii. Additionally, we show that our twogun4complements over-express the GUN4 protein and show a higher Chl content per cell compared to that in the wild type strain. |
| Databáze: | OpenAIRE |
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