Is annexin 1 a multifunctional protein during stress responses?

Abstract

Accumulating evidence suggest that certain annexins can play a role in abiotic stress responses in plants. We found that for one member of the Arabidopsis thaliana annexin gene family, annexin 1 (AnnAt1), loss-of-function mutants are more sensitive to drought stress and gain-of-function mutants are more tolerant. We also found that AnnAt1 is able to regulate accumulation of H(2)O(2) in vivo in Arabidopsis cells based on the observation that the level of ROS accumulation following induction by ABA correlates with the level of AnnAt1 protein in transgenic Arabidopsis plants. Here we provide more commentary on the antioxidant activity of AnnAt1, critically assess the evidence that AnnAt1 and other annexins possess peroxidase activity, emphasize a redox-induced post-translational modification which occurs to AnnAt1 during ABA signaling, and discuss ways this annexin's membrane associations could mediate stress signaling while addressing the potential that AnnAt1 is a multifunctional protein in plants.

Figure 1

Mass spec analyses of in vitro S-glutathionylated AnnAt1. Purified heterologous wild type AnnAt1-His(6) was dissolved in guanidium-HCl and treated with excess of oxidized gluthathione for 30 minutes in room temperature. After dilution protein was then purified using HPLC and was then sequenced with MS-MS to confirm modification of individual cysteine residues.