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The Role of Annexin 1 in Drought Stress in Arabidopsis

Konopka-Postupolska, Dorota and Clark, Greg and Goch, Grażyna and Dębski, Janusz and Floras, Krzysztof and Cantero, Araceli and Fijołek, Bartłomiej and Roux, Stanley and Hennig, Jacek (2009) The Role of Annexin 1 in Drought Stress in Arabidopsis. The role of annexin 1 in drought stress in Arabidopsis, 150 . pp. 1394-1410.

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Annexins act as targets of calcium signals in eukaryotic cells, and recent results suggest that they play an important role in plant stress responses. We found that in Arabidopsis (Arabidopsis thaliana), AnnAt1 (for annexin 1) mRNA levels were upregulated in leaves by most of the stress treatments applied. Plants overexpressing AnnAt1 protein were more drought tolerant and knockout plants were more drought sensitive than ecotype Columbia plants. We also observed that hydrogen peroxide accumulation in guard cells was reduced in overexpressing plants and increased in knockout plants both before and after treatment with abscisic acid. Oxidative protection resulting from AnnAt1 overexpression could be due to the low level of intrinsic peroxidase activity exhibited by this protein in vitro, previously linked to a conserved histidine residue found in a peroxidase-like motif. However, analyses of a mutant H40A AnnAt1 protein in a bacterial complementation test and in peroxidase activity assays indicate that this residue is not critical to the ability of AnnAt1 to confer oxidative protection. To further examine the mechanism(s) linking AnnAt1 expression to stress resistance, we analyzed the reactive S3 cluster to determine if it plays a role in AnnAt1 oligomerization and/or is the site for posttranslational modification. We found that the two cysteine residues in this cluster do not form intramolecular or intermolecular bonds but are highly susceptible to oxidation-driven S-glutathionylation, which decreases the Ca2+ affinity of AnnAt1 in vitro. Moreover, S-glutathionylation of AnnAt1 occurs in planta after abscisic acid treatment, which suggests that this modification could be important in regulating the cellular function of AnnAt1 during stress responses.

Item Type:Article
Subjects:Q Science > QK Botany
R Medicine > RV Botanic, Thomsonian, and eclectic medicine
Divisions:Laboratory of Plant Pathogenesis
ID Code:15
Deposited By: Dr Dorota Konopka-Postupolska
Deposited On:26 Mar 2010 09:34
Last Modified:01 Oct 2015 18:49

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