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Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria
Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusi...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262485/ https://www.ncbi.nlm.nih.gov/pubmed/30428557 http://dx.doi.org/10.3390/antiox7110164 |
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author | López-Maury, Luis Heredia-Martínez, Luis G. Florencio, Francisco J. |
author_facet | López-Maury, Luis Heredia-Martínez, Luis G. Florencio, Francisco J. |
author_sort | López-Maury, Luis |
collection | PubMed |
description | Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusively found in cyanobacteria. TrxC has a modified active site (WCGLC) instead of the canonical (WCGPC) present in most thioredoxins. We have purified it and assayed its activity but surprisingly TrxC lacked all the classical activities, such as insulin precipitation or activation of the fructose-1,6-bisphosphatase. Mutants lacking trxC or over-expressing it were generated in the model cyanobacterium Synechocystis sp. PCC 6803 and their phenotypes have been analyzed. The ΔtrxC mutant grew at similar rates to WT in all conditions tested although it showed an increased carotenoid content especially under low carbon conditions. Overexpression strains showed reduced growth under the same conditions and accumulated lower amounts of carotenoids. They also showed lower oxygen evolution rates at high light but higher Fv’/Fm’ and Non-photochemical-quenching (NPQ) in dark adapted cells, suggesting a more oxidized plastoquinone pool. All these data suggest that TrxC might have a role in regulating photosynthetic adaptation to low carbon and/or high light conditions. |
format | Online Article Text |
id | pubmed-6262485 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-62624852018-11-29 Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria López-Maury, Luis Heredia-Martínez, Luis G. Florencio, Francisco J. Antioxidants (Basel) Article Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusively found in cyanobacteria. TrxC has a modified active site (WCGLC) instead of the canonical (WCGPC) present in most thioredoxins. We have purified it and assayed its activity but surprisingly TrxC lacked all the classical activities, such as insulin precipitation or activation of the fructose-1,6-bisphosphatase. Mutants lacking trxC or over-expressing it were generated in the model cyanobacterium Synechocystis sp. PCC 6803 and their phenotypes have been analyzed. The ΔtrxC mutant grew at similar rates to WT in all conditions tested although it showed an increased carotenoid content especially under low carbon conditions. Overexpression strains showed reduced growth under the same conditions and accumulated lower amounts of carotenoids. They also showed lower oxygen evolution rates at high light but higher Fv’/Fm’ and Non-photochemical-quenching (NPQ) in dark adapted cells, suggesting a more oxidized plastoquinone pool. All these data suggest that TrxC might have a role in regulating photosynthetic adaptation to low carbon and/or high light conditions. MDPI 2018-11-13 /pmc/articles/PMC6262485/ /pubmed/30428557 http://dx.doi.org/10.3390/antiox7110164 Text en © 2018 by the authors. 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 (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article López-Maury, Luis Heredia-Martínez, Luis G. Florencio, Francisco J. Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title | Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title_full | Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title_fullStr | Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title_full_unstemmed | Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title_short | Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria |
title_sort | characterization of trxc, an atypical thioredoxin exclusively present in cyanobacteria |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262485/ https://www.ncbi.nlm.nih.gov/pubmed/30428557 http://dx.doi.org/10.3390/antiox7110164 |
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