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1.
Anne Sawyer Yu Bai Yinghua Lu Anja Hemschemeier Thomas Happe 《The Plant journal : for cell and molecular biology》2017,90(6):1134-1143
Molecular hydrogen (H2) can be produced in green microalgae by [FeFe]‐hydrogenases as a direct product of photosynthesis. The Chlamydomonas reinhardtii hydrogenase HYDA1 contains a catalytic site comprising a classic [4Fe4S] cluster linked to a unique 2Fe sub‐cluster. From in vitro studies it appears that the [4Fe4S] cluster is incorporated first by the housekeeping FeS cluster assembly machinery, followed by the 2Fe sub‐cluster, whose biosynthesis requires the specific maturases HYDEF and HYDG. To investigate the maturation process in vivo, we expressed HYDA1 from the C. reinhardtii chloroplast and nuclear genomes (with and without a chloroplast transit peptide) in a hydrogenase‐deficient mutant strain, and examined the cellular enzymatic hydrogenase activity, as well as in vivo H2 production. The transformants expressing HYDA1 from the chloroplast genome displayed levels of H2 production comparable to the wild type, as did the transformants expressing full‐length HYDA1 from the nuclear genome. In contrast, cells equipped with cytoplasm‐targeted HYDA1 produced inactive enzyme, which could only be activated in vitro after reconstitution of the [4Fe4S] cluster. This indicates that the HYDA1 FeS cluster can only be built by the chloroplastic FeS cluster assembly machinery. Further, the expression of a bacterial hydrogenase gene, CPI, from the C. reinhardtii chloroplast genome resulted in H2‐producing strains, demonstrating that a hydrogenase with a very different structure can fulfil the role of HYDA1 in vivo and that overexpression of foreign hydrogenases in C. reinhardtii is possible. All chloroplast transformants were stable and no toxic effects were seen from HYDA1 or CPI expression. 相似文献
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Expanding the spectral palette of fluorescent proteins for the green microalga Chlamydomonas reinhardtii 总被引:1,自引:0,他引:1
Beth A. Rasala Daniel J. Barrera Jenny Ng Thomas M. Plucinak Julian N. Rosenberg Donald P. Weeks George A. Oyler Todd C. Peterson Farzad Haerizadeh Stephen P. Mayfield 《The Plant journal : for cell and molecular biology》2013,74(4):545-556
3.
Codon reassignment to facilitate genetic engineering and biocontainment in the chloroplast of Chlamydomonas reinhardtii
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There is a growing interest in the use of microalgae as low‐cost hosts for the synthesis of recombinant products such as therapeutic proteins and bioactive metabolites. In particular, the chloroplast, with its small, genetically tractable genome (plastome) and elaborate metabolism, represents an attractive platform for genetic engineering. In Chlamydomonas reinhardtii, none of the 69 protein‐coding genes in the plastome uses the stop codon UGA, therefore this spare codon can be exploited as a useful synthetic biology tool. Here, we report the assignment of the codon to one for tryptophan and show that this can be used as an effective strategy for addressing a key problem in chloroplast engineering: namely, the assembly of expression cassettes in Escherichia coli when the gene product is toxic to the bacterium. This problem arises because the prokaryotic nature of chloroplast promoters and ribosome‐binding sites used in such cassettes often results in transgene expression in E. coli, and is a potential issue when cloning genes for metabolic enzymes, antibacterial proteins and integral membrane proteins. We show that replacement of tryptophan codons with the spare codon (UGG→UGA) within a transgene prevents functional expression in E. coli and in the chloroplast, and that co‐introduction of a plastidial trnW gene carrying a modified anticodon restores function only in the latter by allowing UGA readthrough. We demonstrate the utility of this system by expressing two genes known to be highly toxic to E. coli and discuss its value in providing an enhanced level of biocontainment for transplastomic microalgae. 相似文献
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Enhancing heterologous expression in Chlamydomonas reinhardtii by transcript sequence optimization
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Iddo Weiner Shimshi Atar Shira Schweitzer Haviva Eilenberg Yael Feldman Meital Avitan Mor Blau Avihai Danon Tamir Tuller Iftach Yacoby 《The Plant journal : for cell and molecular biology》2018,94(1):22-31
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A toolkit for Nannochloropsis oceanica CCMP1779 enables gene stacking and genetic engineering of the eicosapentaenoic acid pathway for enhanced long‐chain polyunsaturated fatty acid production
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Eric Poliner Jane A. Pulman Krzysztof Zienkiewicz Kevin Childs Christoph Benning Eva M. Farré 《Plant biotechnology journal》2018,16(1):298-309
Nannochloropsis oceanica is an oleaginous microalga rich in ω3 long‐chain polyunsaturated fatty acids (LC‐PUFAs) content, in the form of eicosapentaenoic acid (EPA). We identified the enzymes involved in LC‐PUFA biosynthesis in N. oceanica CCMP1779 and generated multigene expression vectors aiming at increasing LC‐PUFA content in vivo. We isolated the cDNAs encoding four fatty acid desaturases (FAD) and determined their function by heterologous expression in S. cerevisiae. To increase the expression of multiple fatty acid desaturases in N. oceanica CCMP1779, we developed a genetic engineering toolkit that includes an endogenous bidirectional promoter and optimized peptide bond skipping 2A peptides. The toolkit also includes multiple epitopes for tagged fusion protein production and two antibiotic resistance genes. We applied this toolkit, towards building a gene stacking system for N. oceanica that consists of two vector series, pNOC‐OX and pNOC‐stacked. These tools for genetic engineering were employed to test the effects of the overproduction of one, two or three desaturase‐encoding cDNAs in N. oceanica CCMP1779 and prove the feasibility of gene stacking in this genetically tractable oleaginous microalga. All FAD overexpressing lines had considerable increases in the proportion of LC‐PUFAs, with the overexpression of Δ12 and Δ5 FAD encoding sequences leading to an increase in the final ω3 product, EPA. 相似文献
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Coordinated protein co‐expression in plants by harnessing the synergy between an intein and a viral 2A peptide
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Bei Zhang Madhusudhan Rapolu Sandeep Kumar Manju Gupta Zhibin Liang Zhenlin Han Philip Williams Wei Wen Su 《Plant biotechnology journal》2017,15(6):718-728
A novel approach is developed for coordinated expression of multiple proteins from a single transgene in plants. An Ssp DnaE mini‐intein variant engineered for hyper‐N‐terminal autocleavage is covalently linked to the foot‐and‐mouth disease virus 2A (F2A) peptide with unique ribosome skipping property, via a peptide linker, to create an ‘IntF2A’ self‐excising fusion protein domain. This IntF2A domain acts, in cis, to direct highly effective release of its flanking proteins of interest (POIs) from a ‘polyprotein’ precursor in plants. This is successfully demonstrated in stably transformed cultured tobacco cells as well as in different organs of transgenic tobacco plants. Highly efficient polyprotein processing mediated by the IntF2A domain was also demonstrated in lettuce and Nicotiana benthamiana based on transient expression. Protein constituents released from the polyprotein precursor displayed proper function and accumulated at similar levels inside the cells. Importantly, no C‐terminal F2A extension remains on the released POIs. We demonstrated co‐expression of as many as three proteins in plants without compromising expression levels when compared with those using single‐protein vectors. Accurate differential cellular targeting of released POIs is also achieved. In addition, we succeeded in expressing a fully assembled and functional chimeric anti‐His Tag antibody in N. benthamiana leaves. The IntF2A‐based polyprotein transgene system overcomes key impediments of existing strategies for multiprotein co‐expression in plants, which is particularly important for gene/trait stacking. 相似文献
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Iman Tabatabaei Cristina Dal Bosco Marta Bednarska Stephanie Ruf Jrg Meurer Ralph Bock 《Plant biotechnology journal》2019,17(3):638-649
The genetic transformation of plant cells is critically dependent on the availability of efficient selectable marker gene. Sulfonamides are herbicides that, by inhibiting the folic acid biosynthetic pathway, suppress the growth of untransformed cells. Sulfonamide resistance genes that were previously developed as selectable markers for plant transformation were based on the assumption that, in plants, the folic acid biosynthetic pathway resides in the chloroplast compartment. Consequently, the Sul resistance protein, a herbicide‐insensitive dihydropteroate synthase, was targeted to the chloroplast. Although these vectors produce transgenic plants, the transformation efficiencies are low compared to other markers. Here, we show that this inefficiency is due to the erroneous assumption that the folic acid pathway is located in chloroplasts. When the RbcS transit peptide was replaced by a transit peptide for protein import into mitochondria, the compartment where folic acid biosynthesis takes place in yeast, much higher resistance to sulfonamide and much higher transformation efficiencies are obtained, suggesting that current sul vectors are likely to function due to low‐level mistargeting of the resistance protein to mitochondria. We constructed a series of optimized transformation vectors and demonstrate that they produce transgenic events at very high frequency in both the seed plant tobacco and the green alga Chlamydomonas reinhardtii. Co‐transformation experiments in tobacco revealed that sul is even superior to nptII, the currently most efficient selectable marker gene, and thus provides an attractive marker for the high‐throughput genetic transformation of plants and algae. 相似文献
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Erick Miguel Ramos‐Martinez Lorenzo Fimognari Yumiko Sakuragi 《Plant biotechnology journal》2017,15(9):1214-1224
Microalga‐based biomanufacturing of recombinant proteins is attracting growing attention due to its advantages in safety, metabolic diversity, scalability and sustainability. Secretion of recombinant proteins can accelerate the use of microalgal platforms by allowing post‐translational modifications and easy recovery of products from the culture media. However, currently, the yields of secreted recombinant proteins are low, which hampers the commercial application of this strategy. This study aimed at expanding the genetic tools for enhancing secretion of recombinant proteins in Chlamydomonas reinhardtii, a widely used green microalga as a model organism and a potential industrial biotechnology platform. We demonstrated that the putative signal sequence from C. reinhardtii gametolysin can assist the secretion of the yellow fluorescent protein Venus into the culture media. To increase the secretion yields, Venus was C‐terminally fused with synthetic glycomodules comprised of tandem serine (Ser) and proline (Pro) repeats of 10 and 20 units [hereafter (SP)n, wherein n = 10 or 20]. The yields of the (SP)n‐fused Venus were higher than Venus without the glycomodule by up to 12‐fold, with the maximum yield of 15 mg/L. Moreover, the presence of the glycomodules conferred an enhanced proteolytic protein stability. The Venus‐(SP)n proteins were shown to be glycosylated, and a treatment of the cells with brefeldin A led to a suggestion that glycosylation of the (SP)n glycomodules starts in the endoplasmic reticulum (ER). Taken together, the results demonstrate the utility of the gametolysin signal sequence and (SP)n glycomodule to promote a more efficient biomanufacturing of microalgae‐based recombinant proteins. 相似文献
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Wenzhi Jiang Julian N. Rosenberg Akelia D. Wauchope Jacqueline M. Tremblay Charles B. Shoemaker Donald P. Weeks George A. Oyler 《The Plant journal : for cell and molecular biology》2013,76(4):709-717
Single‐domain antibodies (sdAbs) are powerful tools for the detection, quantification, purification and subcellular localization of proteins of interest in biological research. We have generated camelid (Lama pacos) heavy chain‐only variable VH domain (VHH) libraries against antigens in total cell lysates from Chlamydomonas reinhardtii. The sdAbs in the sera from immunized animals and VHH antibody domains isolated from the library show specificity to C. reinhardtii and lack of reactivity to antigens from four other algae: Chlorella variabilis, Coccomyxa subellipsoidea, Nannochloropsis oceanica and Thalassiosira pseudonana. Antibodies were produced against a diverse representation of antigens as evidenced by sera ELISA and protein‐blot analyses. A phage‐display library consisting of the VHH region contained at least 106 individual transformants, and thus should represent a wide range of C. reinhardtii antigens. The utility of the phage library was demonstrated by using live C. reinhardtii cells to pan for VHH clones with specific recognition of cell‐surface epitopes. The lead candidate VHH clones (designated B11 and H10) bound to C. reinhardtii with EC50 values ≤0.5 nm . Treatment of cells with VHH B11 fused to the mCherry or green fluorescent proteins allowed brilliant and specific staining of the C. reinhardtii cell wall and analysis of cell‐wall genesis during cell division. Such high‐complexity VHH antibody libraries for algae will be valuable tools for algal researchers and biotechnologists. 相似文献
14.
Insights into the Regulation of mRNA Processing of Polycistronic Transcripts Mediated by DRBD4/PTB2, a Trypanosome Homolog of the Polypyrimidine Tract‐Binding Protein
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Javier G. De Gaudenzi Adriana V. Jäger Ronan Izcovich Vanina A. Campo 《The Journal of eukaryotic microbiology》2016,63(4):440-452
15.
Tools for chloroplast transformation in Chlamydomonas: expression vectors and a new dominant selectable marker 总被引:6,自引:0,他引:6
Reverse-genetic studies of chloroplast genes in the green alga Chlamydomonas reinhardtii have been hampered by the paucity of suitable selectable markers for chloroplast transformation. We have constructed a series
of vectors for the targeted insertion and expression of foreign genes in the Chlamydomonas chloroplast genome. Using these vectors we have developed a novel selectable marker based on the bacterial gene aphA-6, which encodes an aminoglycoside phosphotransferase. The aphA-6 marker allows direct selection for transformants on medium containing either kanamycin or amikacin. The marker can be used
to inactivate or modify specific chloroplast genes, and can be used as a reporter of gene expression. The availability of
this marker now makes possible the serial transformation of the chloroplast genome of Chlamydomonas.
Received: 26 October 1999 / Accepted: 28 December 1999 相似文献
16.
Development of iFOX‐hunting as a functional genomic tool and demonstration of its use to identify early senescence‐related genes in the polyploid Brassica napus
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Chinedu Charles Nwafor Junluo Cheng Maoteng Li Qing Xu Jian Wu Lu Gan Qingyong Yang Chao Liu Ming Chen Yongming Zhou Edgar B. Cahoon Chunyu Zhang 《Plant biotechnology journal》2018,16(2):591-602
Functional genomic studies of many polyploid crops, including rapeseed (Brassica napus), are constrained by limited tool sets. Here we report development of a gain‐of‐function platform, termed ‘iFOX (inducible Full‐length cDNA OvereXpressor gene)‐Hunting’, for inducible expression of B. napus seed cDNAs in Arabidopsis. A Gateway‐compatible plant gene expression vector containing a methoxyfenozide‐inducible constitutive promoter for transgene expression was developed. This vector was used for cloning of random cDNAs from developing B. napus seeds and subsequent Agrobacterium‐mediated transformation of Arabidopsis. The inducible promoter of this vector enabled identification of genes upon induction that are otherwise lethal when constitutively overexpressed and to control developmental timing of transgene expression. Evaluation of a subset of the resulting ~6000 Arabidopsis transformants revealed a high percentage of lines with full‐length B. napus transgene insertions. Upon induction, numerous iFOX lines with visible phenotypes were identified, including one that displayed early leaf senescence. Phenotypic analysis of this line (rsl‐1327) after methoxyfenozide induction indicated high degree of leaf chlorosis. The integrated B. napuscDNA was identified as a homolog of an Arabidopsis acyl‐CoA binding protein (ACBP) gene designated BnACBP1‐like. The early senescence phenotype conferred by BnACBP1‐like was confirmed by constitutive expression of this gene in Arabidopsis and B. napus. Use of the inducible promoter in the iFOX line coupled with RNA‐Seq analyses allowed mechanistic clues and a working model for the phenotype associated with BnACBP1‐like expression. Our results demonstrate the utility of iFOX‐Hunting as a tool for gene discovery and functional characterization of Brassica napus genome. 相似文献
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Large‐scale insertional mutagenesis of Chlamydomonas supports phylogenomic functional prediction of photosynthetic genes and analysis of classical acetate‐requiring mutants
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Rachel M. Dent Marina N. Sharifi Alizée Malnoë Cat Haglund Robert H. Calderon Setsuko Wakao Krishna K. Niyogi 《The Plant journal : for cell and molecular biology》2015,82(2):337-351
Chlamydomonas reinhardtii is a unicellular green alga that is a key model organism in the study of photosynthesis and oxidative stress. Here we describe the large‐scale generation of a population of insertional mutants that have been screened for phenotypes related to photosynthesis and the isolation of 459 flanking sequence tags from 439 mutants. Recent phylogenomic analysis has identified a core set of genes, named GreenCut2, that are conserved in green algae and plants. Many of these genes are likely to be central to the process of photosynthesis, and they are over‐represented by sixfold among the screened insertional mutants, with insertion events isolated in or adjacent to 68 of 597 GreenCut2 genes. This enrichment thus provides experimental support for functional assignments based on previous bioinformatic analysis. To illustrate one of the uses of the population, a candidate gene approach based on genome position of the flanking sequence of the insertional mutant CAL027_01_20 was used to identify the molecular basis of the classical C. reinhardtii mutation ac17. These mutations were shown to affect the gene PDH2, which encodes a subunit of the plastid pyruvate dehydrogenase complex. The mutants and associated flanking sequence data described here are publicly available to the research community, and they represent one of the largest phenotyped collections of algal insertional mutants to date. 相似文献