TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

Beebo, A; Zia, A; Kinzel, CR; Herdean, A; Bouhidel, K; Kirchhoff, H; Schoefs, B; Spetea, C

TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

Beebo, A Zia, A Kinzel, CR Herdean, A

Bouhidel, K Kirchhoff, H Schoefs, B Spetea, C

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Publication Type:: Journal Article
Citation:: 2020, pp. 2020.09.18.297978
Issue Date:: 2020-09-18

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Field	Value	Language
dc.contributor.author	Beebo, A
dc.contributor.author	Zia, A
dc.contributor.author	Kinzel, CR
dc.contributor.author	Herdean, A https://orcid.org/0000-0003-2143-0213
dc.contributor.author	Bouhidel, K
dc.contributor.author	Kirchhoff, H
dc.contributor.author	Schoefs, B
dc.contributor.author	Spetea, C
dc.date.accessioned	2021-11-11T23:38:54Z
dc.date.available	2021-11-11T23:38:54Z
dc.date.issued	2020-09-18
dc.identifier.citation	2020, pp. 2020.09.18.297978
dc.identifier.uri	http://hdl.handle.net/10453/151516
dc.description.abstract	<jats:title>SUMMARY</jats:title><jats:p>Photosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of <jats:italic>Arabidopsis thaliana</jats:italic>. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO<jats:sub>2</jats:sub> fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.</jats:p>
dc.language	en
dc.relation.isbasedon	10.1101/2020.09.18.297978
dc.rights	info:eu-repo/semantics/openAccess
dc.title	TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis
dc.type	Journal Article
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	open_access	*
dc.date.updated	2021-11-11T23:38:53Z

Abstract:

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO2 fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.

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http://hdl.handle.net/10453/151516