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Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta

Ultraviolet radiation (UVR; 280–400 nm) has a great impact on aquatic ecosystems by affecting ecophysiological and biogeochemical processes as a consequence of the global change scenario generated by anthropogenic activities. We studied the effect of PAR (P)+UVA (A)+UVB (B) i.e. PAB, on the molecula...

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Autores principales: Mata, M. Teresa, Palma, Armando, García-Gómez, Candela, López-Parages, María, Vázquez, Víctor, Cheng-Sánchez, Iván, Sarabia, Francisco, López-Figueroa, Félix, Jiménez, Carlos, Segovia, María
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Shared Science Publishers OG 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6859423/
https://www.ncbi.nlm.nih.gov/pubmed/31799323
http://dx.doi.org/10.15698/mic2019.11.696
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author Mata, M. Teresa
Palma, Armando
García-Gómez, Candela
López-Parages, María
Vázquez, Víctor
Cheng-Sánchez, Iván
Sarabia, Francisco
López-Figueroa, Félix
Jiménez, Carlos
Segovia, María
author_facet Mata, M. Teresa
Palma, Armando
García-Gómez, Candela
López-Parages, María
Vázquez, Víctor
Cheng-Sánchez, Iván
Sarabia, Francisco
López-Figueroa, Félix
Jiménez, Carlos
Segovia, María
author_sort Mata, M. Teresa
collection PubMed
description Ultraviolet radiation (UVR; 280–400 nm) has a great impact on aquatic ecosystems by affecting ecophysiological and biogeochemical processes as a consequence of the global change scenario generated by anthropogenic activities. We studied the effect of PAR (P)+UVA (A)+UVB (B) i.e. PAB, on the molecular physiology of the unicellular green alga Dunaliella tertiolecta for six days. We assessed the relationship between the triggered UVR stress response and metacaspases and caspase-like (CL)activities, which are proteases denoted to participate in cell death (CD) in phytoplankton. UVR inhibited cell growth and in vivo chlorophyll a fluorescence but did not cause cell death. Western blot analyses reflected that Type-II metacaspases (MCs) are present and appear to be involved in UVR induced-cell stress but not in dark-induced CD in D. tertiolecta. Enzyme kinetics revealed that cleavage of the MCs-reporter substrates RVRR, QRR, GRR, LKR, HEK, and VLK was 10-fold higher than WEHD, DEVD, IETD, and LETD CLs-substrates. The lowest apparent Michaelis-Menten constants (K(M)(ap)) corresponded to RVRRase (37.5 μM) indicating a high affinity by the RVRR substrate. The inhibition of enzymatic activities by using inhibitors with different target sites for hydrolyses demonstrated that from all of the R/ Kase activities only RVRRase was a potential candidate for being a metacaspase. In parallel, zymograms and peptide-mass fingerprinting analyses revealed the identities of such Rase activities suggesting an indirect evidence of possible natural physiological substrates of MCs. We present evidence of type II-MCs not being involved in CD in D. tertiolecta, but rather in survival strategies under the stressful irradiance conditions applied in this study.
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spelling pubmed-68594232019-12-03 Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta Mata, M. Teresa Palma, Armando García-Gómez, Candela López-Parages, María Vázquez, Víctor Cheng-Sánchez, Iván Sarabia, Francisco López-Figueroa, Félix Jiménez, Carlos Segovia, María Microb Cell Research Article Ultraviolet radiation (UVR; 280–400 nm) has a great impact on aquatic ecosystems by affecting ecophysiological and biogeochemical processes as a consequence of the global change scenario generated by anthropogenic activities. We studied the effect of PAR (P)+UVA (A)+UVB (B) i.e. PAB, on the molecular physiology of the unicellular green alga Dunaliella tertiolecta for six days. We assessed the relationship between the triggered UVR stress response and metacaspases and caspase-like (CL)activities, which are proteases denoted to participate in cell death (CD) in phytoplankton. UVR inhibited cell growth and in vivo chlorophyll a fluorescence but did not cause cell death. Western blot analyses reflected that Type-II metacaspases (MCs) are present and appear to be involved in UVR induced-cell stress but not in dark-induced CD in D. tertiolecta. Enzyme kinetics revealed that cleavage of the MCs-reporter substrates RVRR, QRR, GRR, LKR, HEK, and VLK was 10-fold higher than WEHD, DEVD, IETD, and LETD CLs-substrates. The lowest apparent Michaelis-Menten constants (K(M)(ap)) corresponded to RVRRase (37.5 μM) indicating a high affinity by the RVRR substrate. The inhibition of enzymatic activities by using inhibitors with different target sites for hydrolyses demonstrated that from all of the R/ Kase activities only RVRRase was a potential candidate for being a metacaspase. In parallel, zymograms and peptide-mass fingerprinting analyses revealed the identities of such Rase activities suggesting an indirect evidence of possible natural physiological substrates of MCs. We present evidence of type II-MCs not being involved in CD in D. tertiolecta, but rather in survival strategies under the stressful irradiance conditions applied in this study. Shared Science Publishers OG 2019-10-07 /pmc/articles/PMC6859423/ /pubmed/31799323 http://dx.doi.org/10.15698/mic2019.11.696 Text en https://creativecommons.org/licenses/by/4.0/ This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
spellingShingle Research Article
Mata, M. Teresa
Palma, Armando
García-Gómez, Candela
López-Parages, María
Vázquez, Víctor
Cheng-Sánchez, Iván
Sarabia, Francisco
López-Figueroa, Félix
Jiménez, Carlos
Segovia, María
Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title_full Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title_fullStr Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title_full_unstemmed Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title_short Type II-Metacaspases are involved in cell stress but not in cell death in the unicellular green alga Dunaliella tertiolecta
title_sort type ii-metacaspases are involved in cell stress but not in cell death in the unicellular green alga dunaliella tertiolecta
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6859423/
https://www.ncbi.nlm.nih.gov/pubmed/31799323
http://dx.doi.org/10.15698/mic2019.11.696
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