Poster: Oxidative stress

Abs # 88: Arabidopsis OXS2 is a transcription factor in the oxidative stress response

Presenter:	Blanvillain, Robert , robertab@uclink.berkeley.edu
Authors	Blanvillain, Robert  (A)   Ow, David  (A)
Affiliations:	(A): Plant Gene Expression Center, UC Berkeley, USDA

The growth and reproduction of plants, which are sedentary organisms, are highly dependent on their ability to weather the environment. Sudden and extreme changes in external conditions require immediate and effective biochemical responses. Here we report the identification of an Arabidopsis thaliana oxidative stress responsive gene, OXS2, which encodes a zinc finger protein. OXS2 protein is a positive regulator of gene expression and can autoactivate its own promoter. A selection and amplification binding assay (SAAB) revealed a nine-base-pair CT-rich target sequence that is also present in OXS2 promoter. OXS2 protein is also regulated at the level of subcellular localization. OXS2-eGFP (enhanced green fluorescent protein) fusions showed movement from the cytoplasm to the nucleus during stress. Moreover the nucleocytoplasmic shuttling is dependant on Exportin I (XPOI or Crm1). Nuclear accumulation, along with the auto-activation of its own gene, accounts for the higher accumulation of OXS2 mRNA during stress. Transgenic plants expressing OXS2 from the 35S promoter accelerate a commonly recognized survival strategy, the redirection from vegetative growth to flowering. Taken together, these results lead to a model where oxidative stress causes the nuclear accumulation of OXS2, the autoactivation of its own gene, followed by the positive activation of a stress-induced flowering pathway.