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Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas
Microalgae biotechnology has the potential to produce high quality bioproducts in a sustainable manner. Here, Chlamydomonas reinhardtii has shown great potential as a host for biotechnological exploitation. However, low expression of nuclear transgenes is still a problem and needs to be optimized. I...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10138193/ https://www.ncbi.nlm.nih.gov/pubmed/37107706 http://dx.doi.org/10.3390/genes14040948 |
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author | Niemeyer, Justus Fischer, Laura Aylward, Frank O’Neill Schroda, Michael |
author_facet | Niemeyer, Justus Fischer, Laura Aylward, Frank O’Neill Schroda, Michael |
author_sort | Niemeyer, Justus |
collection | PubMed |
description | Microalgae biotechnology has the potential to produce high quality bioproducts in a sustainable manner. Here, Chlamydomonas reinhardtii has shown great potential as a host for biotechnological exploitation. However, low expression of nuclear transgenes is still a problem and needs to be optimized. In many model organisms, viral promoters are used to drive transgene expression at high levels. However, no viruses are known to infect Chlamydomonas, and known viral promoters are not functional. Recently, two different lineages of giant viruses were identified in the genomes of Chlamydomonas reinhardtii field isolates. In this work, we tested six potentially strong promoters from these viral genomes for their ability to drive transgene expression in Chlamydomonas. We used ble, NanoLUC, and mCherry as reporter genes, and three native benchmark promoters as controls. None of the viral promoters drove expression of any reporter gene beyond background. During our study, we found that mCherry variants are produced by alternative in-frame translational start sites in Chlamydomonas. We show that this problem can be overcome by mutating the responsible methionine codons to codons for leucine and by using the 5′-UTR of βTUB2 instead of the 5′-UTRs of PSAD or RBCS2. Apparently, the βTUB2 5′-UTR promotes the use of the first start codon. This could be mediated by the formation of a stem-loop between sequences of the βTUB2 5′-UTR and sequences downstream of the first AUG in the mCherry reporter, potentially increasing the dwell time of the scanning 40S subunit on the first AUG and thus decreasing the probability of leaky scanning. |
format | Online Article Text |
id | pubmed-10138193 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-101381932023-04-28 Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas Niemeyer, Justus Fischer, Laura Aylward, Frank O’Neill Schroda, Michael Genes (Basel) Brief Report Microalgae biotechnology has the potential to produce high quality bioproducts in a sustainable manner. Here, Chlamydomonas reinhardtii has shown great potential as a host for biotechnological exploitation. However, low expression of nuclear transgenes is still a problem and needs to be optimized. In many model organisms, viral promoters are used to drive transgene expression at high levels. However, no viruses are known to infect Chlamydomonas, and known viral promoters are not functional. Recently, two different lineages of giant viruses were identified in the genomes of Chlamydomonas reinhardtii field isolates. In this work, we tested six potentially strong promoters from these viral genomes for their ability to drive transgene expression in Chlamydomonas. We used ble, NanoLUC, and mCherry as reporter genes, and three native benchmark promoters as controls. None of the viral promoters drove expression of any reporter gene beyond background. During our study, we found that mCherry variants are produced by alternative in-frame translational start sites in Chlamydomonas. We show that this problem can be overcome by mutating the responsible methionine codons to codons for leucine and by using the 5′-UTR of βTUB2 instead of the 5′-UTRs of PSAD or RBCS2. Apparently, the βTUB2 5′-UTR promotes the use of the first start codon. This could be mediated by the formation of a stem-loop between sequences of the βTUB2 5′-UTR and sequences downstream of the first AUG in the mCherry reporter, potentially increasing the dwell time of the scanning 40S subunit on the first AUG and thus decreasing the probability of leaky scanning. MDPI 2023-04-21 /pmc/articles/PMC10138193/ /pubmed/37107706 http://dx.doi.org/10.3390/genes14040948 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Brief Report Niemeyer, Justus Fischer, Laura Aylward, Frank O’Neill Schroda, Michael Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title | Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title_full | Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title_fullStr | Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title_full_unstemmed | Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title_short | Analysis of Viral Promoters for Transgene Expression and of the Effect of 5′-UTRs on Alternative Translational Start Sites in Chlamydomonas |
title_sort | analysis of viral promoters for transgene expression and of the effect of 5′-utrs on alternative translational start sites in chlamydomonas |
topic | Brief Report |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10138193/ https://www.ncbi.nlm.nih.gov/pubmed/37107706 http://dx.doi.org/10.3390/genes14040948 |
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