Loss of CpSRP54 function leads to a truncated light-harvesting antenna size in Chlamydomonas reinhardtii

Jeong, Jooyeon; Baek, Kwangryul; Kirst, Henning; Melis, Anastasios; Jin, EonSeon

doi:10.1016/j.bbabio.2016.10.007

Cited by 53 publications

(48 citation statements)

References 62 publications

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“…The truncated, light-harvesting antennae are photosynthetically more productive under high-light and high-density culture conditions than cultures with fully pigmented cells. This improvement is due to alleviation of over-absorption, and dissipation of excess energy by the outer layer of cells in the culture, resulting in improved light penetration deeper into the culture and culture productivity [34,35]. Our results showed that mp3 could be considered as an antenna mutant.…”

Section: Discussionmentioning

confidence: 92%

Development of a Dunaliella tertiolecta Strain with Increased Zeaxanthin Content Using Random Mutagenesis

et al. 2017

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Zeaxanthin is a xanthophyll pigment that is regarded as one of the best carotenoids for the prevention and treatment of degenerative diseases. In the worldwide natural products market, consumers prefer pigments that have been produced from biological sources. In this study, a Dunaliella tertiolecta strain that has 10–15% higher cellular zeaxanthin content than the parent strain (zea1), was obtained by random mutagenesis using ethyl methanesulfonate (EMS) as a mutagen. This mutant, mp3, was grown under various salinities and light intensities to optimize culture conditions for zeaxanthin production. The highest cellular zeaxanthin content was observed at 1.5 M NaCl and 65–85 μmol photons·m−2·s−1, and the highest daily zeaxanthin productivity was observed at 0.6 M NaCl and 140–160 μmol photons·m−2·s−1. The maximal yield of zeaxanthin from mp3 in fed-batch culture was 8 mg·L−1, which was obtained at 0.6 M NaCl and 140–160 μmol photons·m−2·s−1. These results suggest that random mutagenesis with EMS is useful for generating D. tertiolecta strains with increased zeaxanthin content, and also suggest optimal culture conditions for the enhancement of biomass and zeaxanthin production by the zeaxanthin accumulating mutant strains.

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Section: Discussionmentioning

confidence: 92%

Development of a Dunaliella tertiolecta Strain with Increased Zeaxanthin Content Using Random Mutagenesis

et al. 2017

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“…Cas9-mediated gene knock-out has been reported for several genes and the use of donor DNA with RNP, called knock-in, has emerged recently. However, the gene-editing efficiency reported in previous studies was not satisfactory (Shin et al, 2016;Greiner et al, 2017;Jeong et al, 2017a).…”

Section: Discussionmentioning

confidence: 93%

Site-Specific Gene Knock-Out and On-Site Heterologous Gene Overexpression in Chlamydomonas reinhardtii via a CRISPR-Cas9-Mediated Knock-in Method

et al. 2020

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Chlamydomonas reinhardtii is being transformed from a model organism to an industrial organism for the production of pigments, fatty acids, and pharmaceuticals. Genetic modification has been used to increase the economic value of C. reinhardtii. However, low gene-editing efficiency and position-effects hinder the genetic improvement of this microorganism. Recently, site-specific double-stranded DNA cleavage using CRISPR-Cas9 system has been applied to regulate a metabolic pathway in C. reinhardtii. In this study, we proved that site-specific gene expression can be induced by CRISPR-Cas9mediated double-strand cleavage and non-homologous end joining (NHEJ) mechanism. The CRISPR-Cas9-mediated knock-in method was adopted to improve gene-editing efficiency and express the reporter gene on the intended site. Knock-in was performed using a combination of ribonucleoprotein (RNP) complex and DNA fragment (antibiotics resistance gene). Gene-editing efficiency was improved via optimization of a component of RNP complex. We found that when the gene CrFTSY was targeted, the efficiency of obtaining the desired mutant by the knock-in method combined with antibiotic resistance was nearly 37%; 2.5 times higher than the previous reports. Additionally, insertion of a long DNA fragment (3.2 and 6.4 kb) and site-specific gene expression were analyzed. We demonstrated the knockout phenotype of CrFTSY and on-site inserted gene expression of luciferase and mVenus at the same time. This result showed that CRISPR-Cas9-mediated knock-in can be used to express the gene of interest avoiding position-effects in C. reinhardtii. This report could provide a new perspective to the use of gene-editing. Furthermore, the technical improvements in genetic modification may accelerate the commercialization of C. reinhardtii.

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“…This nonhomogeneous light penetration results in a low productivity of the system, the inner layers being almost in the dark [21]. Mutant strains with reduced pigment content per cell resulting either from a truncated antenna size or a lower overall density of photosynthetic units per cell were reported for different species, as C. reinhardtii, C. vulgaris, C. sorokiniana and N. gaditana, being characterized by an increased productivity [22][23][24][25]. In addition, up to 80% of the light absorbed by the external layers is dissipated as heat by the activation of photoprotective processes, with consequent loss of light use efficiency and biomass productivity [26].…”

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Improved lipid productivity in Nannochloropsis gaditana in nitrogen-replete conditions by selection of pale green mutants

Cecchin

Berteotti

Paltrinieri

et al. 2020

Biotechnol Biofuels

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Background: Nannochloropsis gaditana is a photosynthetic unicellular microalgae considered one of the most interesting marine algae to produce biofuels and food additive due to its rapid growth rate and high lipid accumulation. Although microalgae are attractive platforms for solar energy bioconversion, the overall efficiency of photosynthesis is reduced due to the steep light gradient in photobioreactors. Moreover, accumulation of lipids in microalgae for biofuels production is usually induced in a two-phase cultivation process by nutrient starvation, with additional time and costs associated. In this work, a biotechnological approach was directed for the isolation of strains with improved light penetration in photobioreactor combined with increased lipids productivity. Results: Mutants of Nannochloropsis gaditana were obtained by chemical mutagenesis and screened for having both a reduced chlorophyll content per cell and increased affinity for Nile red, a fluorescent dye which binds to cellular lipid fraction. Accordingly, one mutant, called e8, was selected and characterized for having a 30% reduction of chlorophyll content per cell and an almost 80% increase of lipid productivity compared to WT in nutrient-replete conditions, with C16:0 and C18:0 fatty acids being more than doubled in the mutant. Whole-genome sequencing revealed mutations in 234 genes in e8 mutant among which there is a non-conservative mutation in the dgd1 synthase gene. This gene encodes for an enzyme involved in the biosynthesis of DGDG, one of the major lipids found in the thylakoid membrane and it is thus involved in chloroplast biogenesis. Lipid biosynthesis is strongly influenced by light availability in several microalgae species, including Nannochloropsis gaditana: reduced chlorophyll content per cell and more homogenous irradiance in photobioreactor is at the base for the increased lipid productivity observed in the e8 mutant. Conclusions: The results herein obtained presents a promising strategy to produce algal biomass enriched in lipid fraction to be used for biofuel and biodiesel production in a single cultivation process, without the additional complexity of the nutrient starvation phase. Genome sequencing and identification of the mutations introduced in e8 mutant suggest possible genes responsible for the observed phenotypes, identifying putative target for future complementation and biotechnological application.

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Loss of CpSRP54 function leads to a truncated light-harvesting antenna size in Chlamydomonas reinhardtii

Cited by 53 publications

References 62 publications

Development of a Dunaliella tertiolecta Strain with Increased Zeaxanthin Content Using Random Mutagenesis

Development of a Dunaliella tertiolecta Strain with Increased Zeaxanthin Content Using Random Mutagenesis

Site-Specific Gene Knock-Out and On-Site Heterologous Gene Overexpression in Chlamydomonas reinhardtii via a CRISPR-Cas9-Mediated Knock-in Method

Improved lipid productivity in Nannochloropsis gaditana in nitrogen-replete conditions by selection of pale green mutants

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